If RBD backend is used for Nova ephemeral storage, Nova tries to remove
ephemeral storage volume from Ceph in a retry loop: 10 attempts at 1
second intervals, totaling 10 seconds overall - which, due to a thirty
second ceph watcher timeout, might result in intermittent volume
removal failures on Ceph side.
This patch adds params rbd_destroy_volume_retries, defaulting to 12, and
rbd_destroy_volume_retry_interval, defaulting to 5, which multiplied, give
Ceph reasonable amount of time to complete the operation successfully.
Closes-Bug: #1856845
Change-Id: Icfd55617f0126f79d9610f8a2fc6b4c817d1a2bd
6458c3dba5