How to categorize this PR?

/area quality
/kind cleanup
/kind enhancement

What this PR does / why we need it:

This PR is to cleanup the Etcd ConfigMap to :

• Rename the configMap in the format {etcd.Name}-config instead of etcd-bootstrap-<UID>. This is for consistency with other resources that gets created as part of Etcd Reconciliation, like leases, role, rolebinding, etc and also have a proper name config for the configMap instead of bootstrap. The cleanup logic for the existing configMap with older name will be taken up at a later stage after 2 releases. This issue tracks that.
• Make snapshot-count configurable with the flag snapshotCount from spec.etcd section of etcd CR thus the operator is able to control the no.of transactions before committing a snapshot to disk if they want to.
• Use proper URLs for initial-advertise-peer-urls and advertise-client-urls properties of the configMap and thereby fixing [Enhancement] Simplify etcd configuration and use proper URL instead of using @ as separator #476

Previously the fields initial-advertise-peer-urls and advertise-client-urls of the etcd ConfigMap were constructed using an @ separator in the format scheme@peerSvcName@namespace@port which is then parsed by the backup-restore container to construct the full URL to be used by the etcd container as its configuration.

This PR aims to modify that to have the fully qualified URL(s) for each etcd member in the ConfigMap itself which then backup-restore parses and sends only it's corresponding etcd member's URL(s) to the etcd process.

The following is the format in the ConfigMap for the fields initial-advertise-peer-urls & advertise-client-urls.

initial-advertise-peer-urls:
  etcd-main-0:
    - main in-cluster url
    - additional urls if required (e.g. live CPM)
  etcd-main-1:
    - main in-cluster url
    - additional urls if required (e.g. live CPM)
  etcd-main-2:
    - main in-cluster url
    - additional urls if required (e.g. live CPM)
advertise-client-urls:
  etcd-main-0:
    - main in-cluster url
    - additional urls if required (e.g. live CPM)
  etcd-main-1:
    - main in-cluster url
    - additional urls if required (e.g. live CPM)
  etcd-main-2:
    - main in-cluster url
    - additional urls if required (e.g. live CPM)

The additional urls above is used for e.g. in CPM in the context of Gardener use case. For now from code we only populate the main in-cluster URL, but in future we will modify the API to allow passing these additional urls from the Etcd Spec which will get populated here and be subsequently parsed and sent to etcd process.

Which issue(s) this PR fixes:
Fixes #717

Special notes for your reviewer:

Release note:

Enhances Etcd configuration by organizing ConfigMap naming convention, enabling snapshot-count configuration, and rectifying URL issues for improved functionality and consistency

Etcd ConfigMap Naming Update: The naming convention has changed to {etcd.Name}-config for consistency, replacing etcd-bootstrap-<UID>. Unused old ConfigMaps will be removed in v0.27.0