rgw: object expirer: handle resharded buckets

rgw: object expirer: handle resharded buckets

Previously we fetched the bucket instance info which changes during a reshard
causing the bucket info to fail, since the subsequent checks will assume that
would mean a deleted bucket, the expiry hint is purged as well, leaving a non
deleted object as well as a deleted hint. This should fix newer runs of object
expiry processes. Finding out stale expired objects will require more complex
rgw-admin tooling support

Fixes: https://tracker.ceph.com/issues/39495
Signed-off-by: Abhishek Lekshmanan <abhishek@suse.com>