Remove onDidUpdateRepository

Created by: felixfbecker

I noticed that this function, which allowed partial updates of the repository, was never actually called with any partial updates, making it useless for the intended purposes. There was a fair bit of complexity in RepoContainer to enable this so this is a good riddance.

Only in one instance, on the repo settings mirror page, does the prop do something different: It triggers a refetch. That's an isolated circle though and doesn't forward any partial updates up to the RepoContainer.