Add action to remove a single OSD from the crush map

[Xav Paice]

When moving disks around we often want to remove OSDs from the crush map entirely. An action to do this would reduce the risks of such an operation.

[Xav Paice (xavpaice)]

good detailed writeup of some requirements in https://bugs.launchpad.net/charm-ceph-mon/+bug/1813360

[Xav Paice (xavpaice)]

https://review.opendev.org/#/c/757370/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/757370
Committed: https://git.openstack.org/cgit/openstack/charm-ceph-mon/commit/?id=a5ef8d687d1b315138ab5c7076f268e78aab6d35
Submitter: Zuul
Branch: master

commit a5ef8d687d1b315138ab5c7076f268e78aab6d35
Author: Xav Paice <email address hidden>
Date: Mon Oct 12 13:20:13 2020 +1300

    Add actions to reweight and remove OSDs.

    Adds action change-osd-weight, to allow changing the weight of an OSD.

    Adds action purge-osd, to remove an OSD entirely from the crush map.

    Change-Id: Ic1f468c96931a136ba897d4a02b8cd43dfdf056b
    Closes-bug: #1761048