[Backup/Restore cStor] Verify the case of triggering backup when cStor is unhealthy.

[kmova]

This issue was created in response to Originally posted by @mynktl in openebs/velero-plugin#79 (comment)

There were some panics observed when backup was triggered in case of cstor volume being in not-ready state and then subsequent cleanup resulted in panic.

If CVR are not healthy then snapshot will fail.
If CVR are healthy then we can inject this error while restarting the cstor pool pod or killing the cstor-pool-mgmt container

[shashank855]

Looking at the issue, e2e flow should be like;

• Create backup
• Get the pool name where backup is scheduled.
• Inject chaos on pool pod when backup is in progress.
• Backup will be failed (expected).
• Try deleting failed backup (It should get deleted).