Automatic merge from submit-queue (batch tested with PRs 49326, 49394, 49346, 49379, 49399)

more robust stat handling from ceph df output in the kubernetes-master charm create-rbd-pv action

**What this PR does / why we need it**: more robust stat handling from ceph df output in the kubernetes-master charm create-rbd-pv action

**Release note**:
```release-note
more robust stat handling from ceph df output in the kubernetes-master charm create-rbd-pv action
```