ci: fix final status for CLT-only test runs

[sanikolaev]

Fixes a false failure in the test.yml Final status job for CLT-only runs.

When a change only touches test/clt-tests/** and a cached test-kit image exists, Meta intentionally sets run_builds=false. That skips build/ubertest jobs, including the MCL runtime cache probes and runtime builds. Final status must not require those runtime artifacts in that path.

This PR documents the existing run_builds guard around the runtime-artifact check so the intended behavior is clear.

Without this guard, CLT-only cached-image runs can fail even after CLT succeeds with messages like:

mcl_runtime_linux_debug: no cached runtime artifact and build result was skipped
mcl_runtime_linux_release: no cached runtime artifact and build result was skipped
mcl_runtime_windows_debug: no cached runtime artifact and build result was skipped