It was introduced in 69e1e6ca to help node determine faulty shards.
However, the situation is possible in a real-life scenario:
1. Object O is evacuated from shard A to B.
2. Shard A is unmounted because of lower-level errors.
3. We now have object in meta on A and in blobstor on B. Technically we
have it in meta on shard B too, but we still got the error if B goes
to a degraded mode.
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
