Add run-once cleanup gitjobs job

[0xavi0]

After merging #2903 we need:

• turn Cleanup completed gitjobs #2907 into a run-once job when Changes job handling in gitops controller #2903 is merged.
• make sure it's actually run when upgrading 0.10.2->0.10.4
• fix service account used

[0xavi0]

Additional QA

Problem

We need to update the cleanup gitjobs job to delete all the jobs that are created by GitRepos and that are Finished.
We need to test that this is executed when updating Fleet from a previous version.

Solution

• The job should run only once, after updating
• The job should use the right ServiceAccount
• The job should delete all the jobs that are relative to a GitRepo and that succeeded.

Testing

Start using Rancher 2.9.2

• Apply a GitRepo that is successful, update the git repository, so Fleet creates a new job per each new commit. Repeat until you have a few jobs.
• Update Fleet to 2.9.3
• Check that all jobs that succeeded are deleted.
• Check also that after the update Fleet creates a new job per each commit, but this time the job is deleted after it succeeds.