Automatic merge from submit-queue (batch tested with PRs 53778, 58378, 58830). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add storage-backend configuration option to kubernetes-master charm.

**What this PR does / why we need it**: Add storage-backend configuration option to kubernetes-master charm.

**Release note**:
```release-note
Add storage-backend configuration option to kubernetes-master charm.
```