Add controller-runtime based leader election to this operator

[nikhil-thomas]

We had to remove leader-for-life leader election as it was blocking our upgrades.
This is issue is a tracker/remider to add a better leader election (if necessary) in the future.

ref:

• remove leader election #170
• https://docs.okd.io/4.10/operators/operator_sdk/osdk-leader-election.html#osdk-leader-with-lease-election_osdk-leader-election