Helm Chart update: make executor ClusterRole name unique

[bgounon]

Summary

Executor ClusterRole name should be dynamic instead of hard-coded. Without it, you cannot have several namespaced releases of k8up, as it triggers a collision on the executor ClusterRole name and fails.

Checklist

For Helm Chart changes

• Categorize the PR by setting a good title and adding one of the labels:
  bug, enhancement, documentation, change, breaking, dependency
  as they show up in the changelog
• PR contains the label area:chart
• PR contains the chart label, e.g. chart:k8up
• Variables are documented in the values.yaml using the format required by Helm-Docs.
• Chart Version bumped if immediate release after merging is planned
• I have run make chart-docs
• Link this PR to related code release or other issues.

[Kidswiss]

Hi @bgounon

Thank you for the PR!

I like the idea, but just making the name dynamically based on the fullname could also break single installations, if a non-default name is specified.

Instead, you could add a new value under rbac like disableClusterRole. Then the first k8up install can install the clusterrole and all subsequent ones don't.

Another approach could be to disable the rbac completely and deploy the ClusterRoles separately, via the value rbac.create.