.github/workflow: Add explicit platform config to C++ build steps

Add --config=per-x86_64-linux flag to all C++ Bazel build, test, and run
commands in GitHub workflows to ensure consistent platform selection.

Changes:
- check.yml: Add config to cpp-bazel job (build, coverage, benchmark)
- component_integration_tests.yml: Add config to C++ test scenarios build

This ensures the correct GCC toolchain and platform settings are used,
aligning with the platform configurations defined in .bazelrc.

Author: umaucher

.github/workflows/check.yml

@@ -146,11 +146,11 @@ jobs:
           bazelisk-cache: true
 
       - name: Bazel Build
-        run: bazel build //:kvs_cpp
+        run: bazel build --config=per-x86_64-linux //:kvs_cpp
 
       - name: Bazel Unit Test with Coverage
         run: |
-          bazel coverage //:test_kvs_cpp \
+          bazel coverage --config=per-x86_64-linux//:test_kvs_cpp \
             --collect_code_coverage \
             --combined_report=lcov \
             --experimental_generate_llvm_lcov \
@@ -184,4 +184,4 @@ jobs:
           rm ${OUT_FILE}
 
       - name: Bazel Benchmark
-        run: bazel run -c opt //:bm_kvs_cpp
+        run: bazel run --config=per-x86_64-linux -c opt //:bm_kvs_cpp

.github/workflows/component_integration_tests.yml

@@ -46,7 +46,7 @@ jobs:
 
       - name: Build C++ test scenarios with Bazel
         run: |
-          bazel build //tests/cpp_test_scenarios:cpp_test_scenarios
+          bazel build --config=per-x86_64-linux //tests/cpp_test_scenarios:cpp_test_scenarios
 
       - name: Build Rust test scenarios with Bazel
         run: |