[#679] engine: Do not increase error counter on meta mismatch

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>

pkg/local_object_storage/engine/error_test.go

@@ -217,7 +217,7 @@ func TestBlobstorFailback(t *testing.T) {
 		require.True(t, shard.IsErrOutOfRange(err))
 	}
 
-	checkShardState(t, te.ng, te.shards[0].id, 2, mode.ReadOnly)
+	checkShardState(t, te.ng, te.shards[0].id, 0, mode.ReadWrite)
 	checkShardState(t, te.ng, te.shards[1].id, 0, mode.ReadWrite)
 }