Properly handle Canot catch up ClientTs {timestamp} OplogTs {oldest_ts} exception

https://gitlab.raccoongang.com/aliens/prozorro.sale/mirror/blob/master/src/mongodb_mirror/main.py#L199

Here we just raise an error without any handling. We should notify client that he has fallen too far behind. Proper actions from client would be wipe all his data and resync from 0