[tests] migrate low power and 1.2 tests to nexus (#12641)

This commit removes several legacy Python-based certification tests for
Low Power (CSL) and Thread 1.2 features, as they have been migrated to
the Nexus test framework.

Specifically, the following tests and their associated CI workflows
(including packet verification for low power) are removed:
- CSL Transmission and Timeout
- Enhanced Frame Pending and Keep-Alive
- Single Probe and Forward Tracking Series Link Metrics
- SSED Attachment and Parent Selection

The removal of these scripts from tests/scripts/thread-cert/ and
the corresponding GitHub Action workflows reduces CI overhead while
maintaining coverage through the more scalable Nexus tests.

.github/workflows/otbr.yml

@@ -137,12 +137,6 @@ jobs:
             packet_verification: 1
             nat64: 0
             description: "MATN"
-          - otbr_mdns: "mDNSResponder"
-            otbr_trel: 0
-            cert_scripts: ./tests/scripts/thread-cert/border_router/LowPower/*.py
-            packet_verification: 1
-            nat64: 0
-            description: "LowPower"
           - otbr_mdns: "mDNSResponder"
             otbr_trel: 0
             cert_scripts: ./tests/scripts/thread-cert/border_router/internet/*.py

.github/workflows/simulation-1.4.yml

@@ -121,85 +121,6 @@ jobs:
         path: tmp/coverage.info
         retention-days: 1
 
-  packet-verification-low-power:
-    runs-on: ubuntu-24.04
-    env:
-      REFERENCE_DEVICE: 1
-      VIRTUAL_TIME: 1
-      TEST_TIMEOUT: 300
-      OT_VT_USE_UNIX_SOCKET: 1
-      COVERAGE: 1
-      PACKET_VERIFICATION: 1
-      THREAD_VERSION: 1.4
-      MAC_FILTER: 1
-      INTER_OP: 1
-      INTER_OP_BBR: 0
-    steps:
-    - name: Harden Runner
-      uses: step-security/harden-runner@5ef0c079ce82195b2a36a210272d6b661572d83e # v2.14.2
-      with:
-        egress-policy: audit # TODO: change to 'egress-policy: block' after couple of runs
-
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      with:
-        submodules: recursive
-    - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
-      with:
-        python-version: '3.12'
-        cache: pip
-    - name: Bootstrap
-      run: |
-        sudo apt-get update
-        sudo apt-get --no-install-recommends install -y ninja-build lcov
-        python3 -m pip install -r tests/scripts/thread-cert/requirements.txt
-    - name: Build
-      run: |
-        ./script/test build
-    - name: Build with OT_CSL_RECEIVER_LOCAL_TIME_SYNC
-      run: |
-        OT_BUILDDIR="${PWD}/build_csl_receiver_local_time_sync" OT_OPTIONS="-DOT_CSL_RECEIVER_LOCAL_TIME_SYNC=ON" ./script/test build
-    - name: Get Thread-Wireshark
-      run: |
-        ./script/test get_thread_wireshark
-    - name: Run
-      run: |
-        ulimit -c unlimited
-        ./script/test prepare_coredump_upload
-        for i in {1..10}
-        do
-          ./script/test cert_suite ./tests/scripts/thread-cert/v1_2_LowPower*.py
-        done
-    - name: Run with OT_CSL_RECEIVER_LOCAL_TIME_SYNC
-      run: |
-        OT_BUILDDIR="${PWD}/build_csl_receiver_local_time_sync" ./script/test cert_suite ./tests/scripts/thread-cert/v1_2_LowPower*.py
-    - name: Check Crash
-      if: ${{ failure() }}
-      run: |
-          CRASHED=$(./script/test check_crash | tail -1)
-          [[ $CRASHED -eq "1" ]] && echo "Crashed!" || echo "Not crashed."
-          echo "CRASHED=$CRASHED" >> $GITHUB_ENV
-    - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
-      if: ${{ failure() }}
-      with:
-        name: packet-verification-low-power-pcaps
-        path: |
-          *.pcap
-          *.json
-    - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
-      if: ${{ failure() && env.CRASHED == '1' }}
-      with:
-        name: core-packet-verification-low-power
-        path: |
-          ./ot-core-dump/*
-    - name: Generate Coverage
-      run: |
-        ./script/test generate_coverage gcc
-    - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
-      with:
-        name: cov-packet-verification-low-power
-        path: tmp/coverage.info
-        retention-days: 1
-
   packet-verification-1-1-on-1-4:
     runs-on: ubuntu-24.04
     env:
@@ -352,82 +273,11 @@ jobs:
         path: tmp/coverage.info
         retention-days: 1
 
-  thread-1-4-posix:
-    runs-on: ubuntu-24.04
-    env:
-      COVERAGE: 1
-      PYTHONUNBUFFERED: 1
-      READLINE: readline
-      THREAD_VERSION: 1.4
-      OT_NODE_TYPE: rcp
-      USE_MTD: 1
-      VIRTUAL_TIME: 1
-      OT_VT_USE_UNIX_SOCKET: 1
-      INTER_OP: 1
-    steps:
-    - name: Harden Runner
-      uses: step-security/harden-runner@5ef0c079ce82195b2a36a210272d6b661572d83e # v2.14.2
-      with:
-        egress-policy: audit # TODO: change to 'egress-policy: block' after couple of runs
-
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
-      with:
-        submodules: recursive
-    - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
-      with:
-        python-version: '3.12'
-        cache: pip
-    - name: Bootstrap
-      run: |
-        sudo apt-get update
-        sudo apt-get --no-install-recommends install -y libreadline6-dev ninja-build llvm lcov
-        python3 -m pip install -r tests/scripts/thread-cert/requirements.txt
-    - name: Build
-      run: |
-        ./script/test build
-    - name: Run
-      run: |
-        ulimit -c unlimited
-        ./script/test prepare_coredump_upload
-        ./script/test cert tests/scripts/thread-cert/v1_2_LowPower_5_3_01_SSEDAttachment.py
-        ./script/test cert tests/scripts/thread-cert/v1_2_LowPower_6_1_07_PreferringARouterOverAReed.py
-        ./script/test cert tests/scripts/thread-cert/v1_2_router_5_1_1.py
-        ./script/test cert tests/scripts/thread-cert/v1_2_test_csl_transmission.py
-        ./script/test cert tests/scripts/thread-cert/v1_2_test_enhanced_frame_pending.py
-        ./script/test cert tests/scripts/thread-cert/v1_2_test_parent_selection.py
-    - name: Check Crash
-      if: ${{ failure() }}
-      run: |
-          CRASHED=$(./script/test check_crash | tail -1)
-          [[ $CRASHED -eq "1" ]] && echo "Crashed!" || echo "Not crashed."
-          echo "CRASHED=$CRASHED" >> $GITHUB_ENV
-    - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
-      if: ${{ failure() }}
-      with:
-        name: thread-1-4-posix-pcaps
-        path: "*.pcap"
-    - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
-      if: ${{ failure() && env.CRASHED == '1' }}
-      with:
-        name: core-thread-1-4-posix
-        path: |
-            ./ot-core-dump/*
-    - name: Generate Coverage
-      run: |
-        ./script/test generate_coverage gcc
-    - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
-      with:
-        name: cov-thread-1-4-posix
-        path: tmp/coverage.info
-        retention-days: 1
-
   upload-coverage:
     needs:
     - thread-1-4
-    - packet-verification-low-power
     - packet-verification-1-1-on-1-4
     - expects
-    - thread-1-4-posix
     runs-on: ubuntu-22.04
     steps:
     - name: Harden Runner