Cannot set rbd_flatten_volume_from_snapshot

[Tiago Pasqualini da Silva]

Currently, cinder-ceph charm does not allow the configuration of rbd_flatten_volume_from_snapshot, even though the cinder RBD driver allows it[1].

This means that a volume created from snapshots will always be dependent on the snapshot, thus making it impossible to remove the parent snapshot.

[1] https://docs.openstack.org/cinder/queens/configuration/block-storage/drivers/ceph-rbd-volume-driver.html

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/653455
Committed: https://git.openstack.org/cgit/openstack/charm-cinder-ceph/commit/?id=2f8b158b152d1e39022cb69cdde0bd906244a418
Submitter: Zuul
Branch: master

commit 2f8b158b152d1e39022cb69cdde0bd906244a418
Author: Liam Young <email address hidden>
Date: Wed Apr 17 14:49:04 2019 +0000

    Allow users to choose to flattern volumes

    Expose rbd_flatten_volume_from_snapshot to the user which allows
    then to flatten volumes created from snapshots to remove
    dependency from volume to snapshot.

    Change-Id: I22a3c82535efac5334dd5deaadbba0dd1eae83ab
    Closes-Bug: #1824582