Returns true if given host is local host
Finds the DCs of the contact points and returns hosts in those DC(s) from allHosts
Sorts nodes in the following order: 1.
Sorts nodes in the following order:
1. local host
2. live nodes in the same DC as contactPoints
3. down nodes in the same DC as contactPoints
Nodes within a group are ordered randomly. Nodes from other DCs are not included.