When we merge a PR programmatically usinggh pr merge --auto --squash, the Github auto handles the merge after all checks are passed. So, apull_request event does not get triggered, and a merge commit is pushed tomain bygithub-actions[bot]. This change handles that case.

I also extracted all dependable logic to a separate workflow for better control and restored the original state ofcontrib.yaml so that cla can work as expected for Community PRs.