configure-projects: more verbose squash commit template

This should at least prevent commit message contents from being lost on a squash merge where the user doesn't select a commit message. It may however be noisy if there are fixup commits involved.

Maybe should contain MR title and body as well? (Now contains title.)

Now only calls time.sleep() when saving a project, which should drastically shorten most runs. The previous call was unnecessary, since projects are already front-loaded and no requests are being made between projects.

Bug: T366624