Description

This allows to configure existingClaim as storage and affinity for the kubernetes-etcd-backup chart.

Checklist

[x] This PR contains a description of the changes I'm making
[x] I updated the version in Chart.yaml
[x] I updated the changelog with an artifacthub.io/changes annotation in Chart.yaml, check the example in the documentation.
[x] I updated applicable README.md files using pre-commit run
[ ] I documented any high-level concepts I'm introducing in docs/
[x] CI is currently green and this is ready for review
[ ] I am ready to test changes after they are applied and released