[github] move nexus core and trel tests to nexus workflow (#12631)

This commit moves the execution of nexus `core` and `trel` tests from
the `toranj.yml` GitHub Actions workflow to the `nexus.yml` workflow.
It separates the tests into dedicated jobs (`nexus-core-tests` and
`nexus-trel-tests`) to improve parallelism and organization. The
existing nexus test job is also renamed to `nexus-cert-tests` to
better reflect its purpose.

.github/workflows/nexus.yml

@@ -45,7 +45,8 @@ permissions:
 
 jobs:
 
-  nexus-tests:
+  nexus-cert-tests:
+    name: nexus-cert-tests
     runs-on: ubuntu-24.04
     steps:
     - name: Harden Runner
@@ -72,3 +73,59 @@ jobs:
     - name: Run Nexus Tests
       run: |
         top_builddir=build/nexus ./tests/nexus/run_nexus_tests.sh
+
+  nexus-core-tests:
+    name: nexus-core-tests
+    runs-on: ubuntu-24.04
+    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
+
+    - name: Bootstrap
+      env:
+        PR_BODY: "${{ github.event.pull_request.body }}"
+      run: |
+        sudo apt-get update
+        sudo apt-get --no-install-recommends install -y ninja-build lcov
+
+    - name: Build Nexus
+      run: |
+        ./tests/nexus/build.sh
+
+    - name: Run Core Tests
+      run: |
+        ctest -L core --output-on-failure
+
+  nexus-trel-tests:
+    name: nexus-trel-tests
+    runs-on: ubuntu-24.04
+    steps:
+    - name: Harden Runner
+      uses: step-security/harden-runner@5ef0c079ce82195b2a36a210272d6b661572d83e # v2.14.2
+      with:
+        egress-policy: audit # TODO: change to 'egress-policy: block' after couple of runs
+
+    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+      with:
+        submodules: recursive
+
+    - name: Bootstrap
+      env:
+        PR_BODY: "${{ github.event.pull_request.body }}"
+      run: |
+        sudo apt-get update
+        sudo apt-get --no-install-recommends install -y ninja-build lcov
+
+    - name: Build Nexus
+      run: |
+        ./tests/nexus/build.sh trel
+
+    - name: Run Core Tests
+      run: |
+        ctest -L trel --output-on-failure

.github/workflows/toranj.yml

@@ -206,32 +206,6 @@ jobs:
       run: |
         ./tests/toranj/build.sh posix-15.4
 
-  nexus:
-    name: nexus
-    runs-on: ubuntu-24.04
-    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
-    - name: Bootstrap
-      env:
-        PR_BODY: "${{ github.event.pull_request.body }}"
-      run: |
-        sudo apt-get update
-        sudo apt-get --no-install-recommends install -y ninja-build lcov
-    - name: Build & Run
-      run: |
-        ./tests/nexus/build.sh
-        ctest -L core --output-on-failure
-        git clean -dfx
-        ./tests/nexus/build.sh trel
-        ctest -L trel --output-on-failure
-
   upload-coverage:
     needs:
     - toranj-cli