manifest: Track specific revision of repohooks

* 17.1/18.1/19.1 all track `master` for this repo.
* 17.1 is the only one of these where soong lacks
  license declaration support, so as of March, 2025
  17.1 builds all fail.
* Premptively track current HEAD of repohooks to
  avoid future issues.

Reference: I5ae3aedfce2596db7eb4d7d41842d94fd3be21bf
Change-Id: If8caab90c834221192de53e61db9bfb0e7fe6bfc