balancerStop command waits for the current balancer round to finish before returning a response to the user.

Since the migration timeout (receiveChunkWaitForRangeDeleterTimeoutMS, set to 90 sec) is bigger than the balancerStop maxTimeMS parameter, a balancerStop command failure would either hide a more valuable error pointing to the migration process or raise an expected error on slow variants.

The purpose of this ticket is to increase the timeout of the balancerStop called from the ShardedClusterFixture on tearDown in order to avoid hiding migration errors and improve the debugability.