Enable failover on replica pod

Status quo

• We have a hybrid deployment with 3 VMs and 1 pod
• The pod has replica-priority of 0 meaning it participates as a replica but will never be elected primary during a failover

Next steps

• Set replica-priority to a non-zero value.
• We can now failover to the pod.
• We can test explicit failover and sentinel-triggered election.

Outcome

We have the ability to failover back and forth between VMs and pods, and discover odd behaviours on the kubernetes-based setup.