PG: do not choose stray osds as async_recovery_targets

PG: do not choose stray osds as async_recovery_targets

Without this change, we might accept stray osds as async_recovery_targets,
and need to ensure that they get a chance to become part of the acting set
after recovery is over.

However, when choose_acting() is called in the Recovered state, we set
restrict_to_up_acting=true, which does not allow them to get back to the
acting set.

Therefore, similar to backfill, do not allow stray osds to become
async_recovery_targets.

Signed-off-by: Neha Ojha <nojha@redhat.com>