The first invocation of `removeShard`, if retried after a stepdown may actually remove the shard instead of just putting it into 'draining' mode. This makes tests running under the continuous config stepdown suite fail intermittently at lines, which call removeShard.

This ticket is to figure out what to do about these tests. We should either blacklist them or change them to expect that removeShard might not find the shard (with an appropriate check beforehand that the shard exists).

Alternatively, we can change the removeShard implementation on mongos to not fail if it found the shard initially, but then got ShardNotFound from the config server.