Remove time dependency of Backup-Restore for Leader Election

[ishan16696]

How to categorize this issue?
/kind enhancement

Stories:

1. To remove time coupled backup-restore's actions on leadership change.

What would you like to be added:

• Removing this polling mechanism in leader-election of backup-restore with something like EtcdServer.leaderChangedNotify

Motivation (Why is this needed?):

1. Currently, this polling mechanism in leader-election of backup-restore makes backup-restore time dependent for taking action on leadership change. We want to use some kind of events by which etcd itself can notify its sidecar about leadership change.
2. Moving etcd to its latest version is important as it contains the new fixes/feature like EtcdServer.leaderChangedNotify which we gonna use in our implementation.
3. Although EtcdServer.leaderChangedNotify is suppose to be used by embedded etcd but we found out that every etcd starts as embedded etcd. Please refer: here
4. With this Golang app which will bootstarp etcd: we will be able to move to Distroless base image and will be able to remove our dependency on etcd custom image.

Acceptance Criteria:

• New Golang app which starts a etcd should be able to form a multi-node etcd cluster without much design change.
• It shouldn’t effect or cause any hindrance to our multi-node etcd features in any form.

[ishan16696]

cc @unmarshall @aaronfern @abdasgupta @shreyas-s-rao