[CI] clang-format job shouldn't block reverts

When reverting a patch and the previous code wasn't clang-format-clean, the git-clang-format CI job fails, preventing auto merges. The CI job shouldn't run/fail when the PR is a revert (e.g., as indicated by a title starting with "Revert ").

Start by locating the CI configuration that defines the git-clang-format job and read how pull-request titles are exposed to it. Verify the job is skipped for titles beginning with "Revert " while still running for ordinary pull requests, so reverts no longer block auto merges.

Written by the indexing model from the issue text.