ReplicatedPG::_scrub: don't bail early for snapdir

Fixes: #7937
Signed-off-by: Samuel Just <sam.just@inktank.com>
Merge pull request #1580 from ceph/wip-7937

osd: fix scrub logic for snapdir object

Reviewed-by: Samuel Just <sam.just@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
osd/: track num_objects_omap in pg stats

Fixes: #7831
Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG::agent_choose_mode: exclude omap objects for ec base pool

Fixes: #7831
Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG::agent_choose_mode: use num_user_objects for target_max_bytes calc

Signed-off-by: Samuel Just <sam.just@inktank.com>
ReplicatedPG::agent_choose_mode: improve debugging

Signed-off-by: Samuel Just <sam.just@inktank.com>
Merge remote-tracking branches 'origin/wip-sam-testing2', 'upstream/wip-7659', 'origin/wip-7904', 'origin/wip-7916', 'origin/wip-7942' and 'origin/wip-7964' into wip-sam-testing