ci: add missing config-variables to actionlint.yaml

Add BENCHMARKING_PLATFORM_GL_PROJECT_ID and APM_SDKS_BENCHMARKS_GL_PROJECT_ID
to the actionlint config-variables list. These are referenced in
go-versions-changed.yml via vars.* context and must be declared to
suppress actionlint false-positive failures.

Author: kakkoyun

.github/actionlint.yaml

@@ -9,3 +9,5 @@ self-hosted-runner:
 # Configuration variables used in workflows
 config-variables:
   - DD_K9_LIBRARY_GO_APP_ID
+  - BENCHMARKING_PLATFORM_GL_PROJECT_ID
+  - APM_SDKS_BENCHMARKS_GL_PROJECT_ID