Simplify system hook testing and guarantee test will fire

The change in !11728 (merged) would cause an arbitrary project to be chosen to test system hooks, and it's likely that the project would not have any commits or relevant commits to test the hook. This would prevent admins from verifying that the hook fired. Instead of trying to create a representative hook dynamically, just send static data to guarantee the hook will actually be tested.

Closes #37067 (closed)