Fix duplicated branch creation/deletion events when using Web UI
When deleting a branch, this is what was happening:
- DeleteBranchService calls EventCreateService and creates an event.
- The call to repository.rm_branch triggers the GitHooksService.
- This, in turn, calls GitPushService and then calls EventCreateService again.
5145706c now makes it no longer necessary for DeleteBranchService and CreateBranchService to create an event.
Closes #4304 (closed)