Better repo maintenance job preserve

[Lyndon-Li]

At present, Velero by default preserve the last 3 repo maintenance jobs so that the job's completion status and logs can be retrieved for troubleshooting and observability purpose.

However, there are gaps to expected best solution:

1. It is better that users could observe the repo maintenance result from the backupRepository CR directly, so that they don't need to match the backupRepository CR to the maintenance job
2. It is better that the repo maintenance logs could be preserved with the same lifecycle as other Velero logs
3. For Kopia repo, there are quickMaintenance and fullMaintenance and fullMaintenance is more complex, more informative. So it is better that users could observe the status of fullMaintenance and quickMaintenance separately and fullMaintenance status should be preserved longer
4. Once we can better preserve the observability and logs, there is no need to preserve the maintenance job objects themselves