feat: Added labels to easily find secrets what created for cluster

[Tom910]

What this PR does:

Right now cass-operator create 3 secret per cluster

• ${nameCluster}-superuser
• ${Datacenter.Name}-keystore
• ${Datacenter.Name}-ca-keystore

and only one ${nameCluster}-superuser has base labels and so, I can't find all the secrets created for a cluster with a command like kubectl get secret -l 'k8ssandra.io/cluster-name=my-cluster'. My cases - I want to delete all secrets after deleting a cluster (right now I generate a name but using a label would be easy)

Which issue(s) this PR fixes: Fixes #

Checklist

• [ ] Changes manually tested
• [ ] Automated Tests added/updated
• [ ] Documentation added/updated
• [x] CHANGELOG.md updated (not required for documentation PRs)
• [x] CLA Signed: DataStax CLA

[burmanm]

Hi, thanks for the PR. Some other things that could be nice would be adding a test in secrets_test.go to verify the labels are there. And of course, we could autodelete them by setting a controller reference to all generated secrets so that deletion of CassandraDatacenter deletes the secrets also without manual process.

[adejanovski]

Hi @Tom910,

do you still plan to work on this PR?

Thanks

[burmanm]

Closing this in favor of https://github.com/k8ssandra/cass-operator/pull/608