Clean up the older configmaps with the naming format etcd-bootstrap-<UID> after 2 releases

[anveshreddy18]

How to categorize this issue?

/area control-plane
/kind cleanup

What would you like to be added:

The PR #812 renames the Etcd ConfigMap to {etcd.Name}-config format from the previous format of etcd-bootstrap-<UID> among few other changes. This is for consistency with other resources that gets created as part of Etcd Reconciliation.

With this, when the druid is upgraded to the version that contains this PR, it creates a new configMap with name as {etcd.Name}-config, leaving the previously existing configMaps with name etcd-bootstrap-<UID> as is for now i.e no cleanup is done in the PR. This is done to support a smooth downgrade/upgrade path without complicating the cleanup process of unused configMaps every time a downgrade & upgrade happens.

But, we do not want unused orphan resources lying in the cluster for a long time. This issue acts as the tracker for removing these unused configmaps after 2 releases i.e with v0.27.0 so that by then downgrade to a previous version would also use the same configMap, removing the dependency on the previous naming convention.

Why is this needed:

To remove the unused orphan resources lying in the cluster.