Pruning soft-deleted volume deleted_manila_share_XXX failed

[Carthaca]

We need to follow up on #116

We rename and defer the deletion to be done by the prune job.
But what is missing: start split clone job to make the to be deleted shares independent to finally be able to get rid of them.

[Carthaca]

Also consider the thoughts from the PTG https://etherpad.opendev.org/p/caracal-ptg-manila section Deferred deletion

[kpawar-sap]

After manually deleting leftover volumes from qa-de-1 netapp filers by @Carthaca , I ran script from https://github.com/kayrus/velero-plugin-for-openstack/tree/cli, which creates child shares and delete them. No repro of above error found.