Adds and fixes small things

[ishan16696]

What this PR does / why we need it:

1. This commit adds a etcd-config.yaml file. It will be useful in running single member etcd and backup-restore locally for testing purposes. Just have to export ENV: ETCD_CONF=example/00-etcd-config.yaml
2. This commit set the HTTP status to StatusServiceUnavailable when backup-restore is in StateUnknown.
3. This commit set the HTTP status to StatusOK when backup-restore is in StateFollower or StateLeader.
4. This commit removes the wrong snapshot compression time calculation as compression is done in this go routine. so it was more or less calculating pipe creation time. More info: https://pkg.go.dev/io#Pipe
5. This commit adds small fixes.

Which issue(s) this PR fixes: Fixes #

Special notes for your reviewer:

Release note:

set the HTTP status to `StatusServiceUnavailable` when backup-restore is in `StateUnknown`.

set the HTTP status to `StatusOK` when backup-restore is in `StateFollower` or `StateLeader`.

[ishan16696]

/cla

[gardener-robot]

@ishan16696 I reached out successfully to the cla-assistant to recheck this pull request.

[ishan16696]

/ping @gardener/etcd-druid-maintainers

[gardener-robot]

@gardener/etcd-druid-maintainers

Message

/ping @gardener/etcd-druid-maintainers

[abdasgupta]

Do we need this PR?

[gardener-robot]

@ishan16696 You need rebase this pull request with latest master branch. Please check.

[ishan16696]

closing this PR as PR becomes very old, I will open a separate PR(s) for necessary changes. /close