Fix image from volume upload ERRORs and WARNINGs with Ceph RBD

By resetting image_upload_use_cinder_backend to upstream default.

When uploading volume to glance image, cinder looks at the backend's
image_upload_use_cinder_backend config knob to decide whether to try link
the glance image to a cloned volume made by cinder, i.e. by doing all work
locally and only updating glance's locations for the image (when the knob
is set to True). However, after all [1], [2] and [3], which happens since
Victoria, this option requires further config from user (using volume type
with image_service:store_id property (aka extra spec) set to the desired
glance store (even if there is only one cinder store configured).

Please read the bug report as to why the option removal is the
best option (TL;DR it is the most compatible approach).

[1] https://review.opendev.org/c/openstack/kolla-ansible/+/708114
[2] https://review.opendev.org/c/openstack/glance_store/+/746556
[3] https://review.opendev.org/c/openstack/cinder/+/661676

Closes-Bug: #1991516
Change-Id: Ife87ee0241d907a0c407eb21811a354ed1734408

ansible/roles/cinder/templates/cinder.conf.j2

@@ -137,7 +137,6 @@ rados_connect_timeout = 5
 rbd_user = {{ ceph_cinder_user }}
 rbd_secret_uuid = {{ cinder_rbd_secret_uuid }}
 report_discard_supported = True
-image_upload_use_cinder_backend = True
 {% endif %}
 
 {% if enable_cinder_backend_nfs | bool %}

releasenotes/notes/bug-1991516-cc280aa71e8dc417.yaml

+---
+upgrade:
+  - |
+    ``image_upload_use_cinder_backend = True`` is no longer set on the
+    Cinder's default Ceph RBD backend, the common upstream default is
+    now used (``False`` currently).
+    See also `LP#1991516 <https://launchpad.net/bugs/1991516>`__
+fixes:
+  - |
+    ``image_upload_use_cinder_backend = True`` is no longer set on the
+    Cinder's default Ceph RBD backend. Related ERRORs and WARNINGs in
+    Cinder and Glance logs are prevented.
+    `LP#1991516 <https://launchpad.net/bugs/1991516>`__