Remove or explicitly test for deprecated hosting service support.
Review Request #13185 — Created Aug. 2, 2023 and submitted
This updates code to stop using hosting service support that has been
deprecated since Review Board 4 (those that now show deprecation
warnings). This primarily appliese to GitLab and to unit tests.
Unit tests now also explicitly check for deprecation warnings, avoiding
any unwanted warnings during test runs and helping us locate and remove
All unit tests pass.
Saw that the hosting service warnings were gone.