osd: propagate base pool application_metadata to tiers
If there is application metadata on the base pool, it should be mirrored
to any other tiers in the set. This aligns with the fact that the
'ceph osd pool application ...' commands refuse to operate on a non-base
pool.
This fixes problems with accessing tiers (e.g., cache tiers) when the
cephx cap is written in terms of application metadata.
Fixes: https://tracker.ceph.com/issues/49788 Signed-off-by: Sage Weil <sage@newdream.net>