Skip pre and post checkout hooks for empty
What does this MR do?
This merge request removes pre_get_sources and post_get_sources from the empty strategy.
Why was this MR needed?
This is needed because it's confusing that the empty and none handle hooks differently.
We will address the need for pre and post hooks in a different way, like with GitLab Steps.
What's the best way to test this MR?
Unit tests.