test: minor case fix

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
mon: obsolete osdmonitor_prepare_command

And the mon_advanced_debug_mode option that is only used in the context
of osdmonitor_prepare_command.

http://tracker.ceph.com/issues/9245 Fixes: #9245

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
tests: remove tests requiring osdmonitor_prepare_command

Although they have been useful, their maintenance and fragility caused
more trouble than their benefits.

Signed-off-by: Loic Dachary <loic-201408@dachary.org>
Merge pull request #2636 from dachary/wip-9245-test-mon-pending

mon: obsolete osdmonitor_prepare_command

Reviewed-by: Sage Weil <sage@redhat.com>