High: PE: Bug lf#2445 - Avoid relying on stickness for stable clone placement

Pre-allocate clone instances to their existing location even in the
absence of stickiness - under most circumstances.

Use stcikiness to decide when to rebalance instance placement when
clone-node-max is greater than 1

Mercurial revision: 072f543fb2b3ffc41d02c5c42eda1b9f743b7954