Add parameters enable leader balance for specifed consensus protocol class

Add parameters:

1. enable_auto_leader_balance_for_ratis: enable balance the RegionGroups' leaders for Ratis consensus protocol, default is false since the Ratis is unstable for this function.
2. enable_auto_leader_balance_for_multileader: enable balance the RegionGroups' leaders for MultiLeader consensus protocol, default is true since the MultiLeader is depends on this function to distribute leader.