Integration/e2e tests for etcd-wrapper component

[shreyas-s-rao]

What would you like to be added:
Integration and/or e2e tests for etcd-wrapper, so that PRs and releases are thoroughly tested before integrating into etcd-druid.

• Decide whether to have integration or e2e tests for etcd-wrapper
• Write integration/e2e tests
• Provide easy method for local testing (possibly using KinD cluster)
• Integrate with CICD pipeline

Why is this needed:
Without integration tests running on etcd-wrapper, it is possible that a PR that works fine within etcd-wrapper may fail to play well with etcd-backup-restore when integrated into etcd-druid. It is better to catch it early, within etcd-wrapper itself, with the help of integration/e2e tests running on every PR and release.

/area quality

[gardener-ci-robot]

The Gardener project currently lacks enough active contributors to adequately respond to all issues.
This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Reopen this issue with /reopen
• Mark this issue as fresh with /remove-lifecycle rotten

/close