ci: Ignore known warnings in CI build

.gitlab/ci/ignore_build_warnings.txt

@@ -5,3 +5,4 @@ Warning: Deprecated: Command 'sign_data' is deprecated. Use 'sign-data' instead.
 Warning: Deprecated: Command 'extract_public_key' is deprecated. Use 'extract-public-key' instead.
 CryptographyDeprecationWarning
 warning: unknown kconfig symbol 'EXAMPLE_ETH_PHY_IP101' assigned to 'y'
+WARNING: The following Kconfig variables were used in "if" clauses

test/apps/build_test/CMakeLists.txt

@@ -2,10 +2,6 @@
 # in this exact order for cmake to work correctly
 cmake_minimum_required(VERSION 3.16)
 
-# (Not part of the boilerplate)
-# This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.
-set(EXTRA_COMPONENT_DIRS $ENV{IDF_PATH}/examples/common_components/protocol_examples_common)
-
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 idf_build_set_property(MINIMAL_BUILD ON)
 project(mqtt_tcp)

test/apps/build_test/main/idf_component.yml

@@ -1,4 +1,6 @@
 dependencies:
-  espressif/mqtt:
-    version: "*"
-    override_path: "../../../.."
+    espressif/mqtt:
+        version: "*"
+        override_path: "../../../.."
+    protocol_examples_common:
+        path: ${IDF_PATH}/examples/common_components/protocol_examples_common