Simplify handling of GitRepo status resources

[aruiz14]

Is your feature request related to a problem? Please describe.
Up to now, Fleet GitRepo status contained only partial information, which required the UI to perform additional calculation (including iterate over BundleDeployments) in order to obtain a list of resources for a GitRepo.

Describe the solution you'd like
rancher/fleet#3186 is evolving the GitRepo status schema in order to contain the necessary information. From the dashboard's perspective, it's not a breaking, since the field being changed is not consumed at the moment. However, we can take the chance to reduce the mentioned calculations and just consume the new status field.

Describe alternatives you've considered
The future server-side pagination will also allow to improve the performance even further, but these changes will only make adoption easier.

Additional context
This is the final step after multiple recent refactoring with the goal of improving the performance of this UI section:

• [SURE-9104] Improve Fleet Performance #12424
• Follow-up on improving Fleet performance #12895
• Feature Request: extend GitRepoStatus for easier differentiation of per-cluster state fleet#3186

[yonasberhe23]

unit tests adequately cover this update. No manual validation is required. Closing this ticket.