rgw cannot find keyring after config file is minimized
Given a ceph.conf file like this:
[client.radosgw.gateway] keyring = /etc/ceph/ceph.client.radosgw.keyring
When converting to the new minimized configuration file format using the "ceph config generate-minimal-conf" command, the gateway configurations are removed. If the keyring location was one of the values and it pointed to a location other than /var/lib/ceph/radosgw/ceph-radosgw.gwname/keyring, the radosgw service cannot start because it cannot find the keyring and it cannot ask the monitor since it doesn't have a keyring to talk to the monitor.
The generate-minimal-conf command should either NOT remove parameters that cannot be stored in the monitor, or at least warn the user that some parameters could not be converted so they can be added to the new config file as needed.