[CI] Let sycl-devops-pr/** branches trigger pre/post-commit

[aelovikov-intel]

In #9950 I envisioned a setup when there will be a dedicated devops pre-commit task that would create fake branch/PR in the repository to verify changes affecting CI. I later realized that we can just push the source branch for such a PR directly to origin and use that for testing.

As such, rename which branch is allowed to trigger post-commit and allow the same for pre-commit. Future changes are expected to be done like this:

• create branch sycl-devops-pr/<name> in intel/llvm repo, it will
  run post-commit testing.
• create PR out of that branch
• create an extra draft PR with a target branch set to the same
  sycl-devops-pr/<name>, that will run pre-commit testing.

[aelovikov-intel]

Tested
Post-commit: https://github.com/intel/llvm/actions/runs/5328224599
Pre-commit: https://github.com/intel/llvm/actions/runs/5328099732

I've cancelled both of the runs after initial/first task finished because the trigger itself is being changed in this PR.

[steffenlarsen]

I like this idea!