osd: Remove usage of unsupported objstores for QoS

osd: Remove usage of unsupported objstores for QoS

mClock is supported on Bluestore and a check is currently done to eliminate other unsupported object stores.
With Filestore no longer in the code base, this check can be removed.
In addition, make sure that osd bench will no longer run on setups with memstore.

Fixes: https://tracker.ceph.com/issues/59531
Signed-off-by: Aishwarya Mathuria <amathuri@redhat.com>
(cherry picked from commit 18043c5e88d241f43b8fd23a8cbc1b15a3854de9)

Conflicts:
  - file: src/osd/OSD.cc
    comment: `OSD::maybe_override_cost_for_qos()` was removed as part of the backport
      that included mClock changes for PG delete operation