Add labels for Jobs to mark them as idempotent for stackablectl demo install

[xeniape]

This is a follow-up issue to #333. Only the first suggested solution was implemented there.

The second one states: Add labels to certain jobs that are idempotent (safe to be recreated and run again), and jobs that should be ignored (initial setup jobs, eg: for Keycloak).

This is needed for idempotent demo installations and to minimize the work a developer needs to do to upgrade demos. For more context, check the previous issue.

[NickLarsenNZ]

This could require a bit of work.

For plainYaml it would be easy-ish, but for helmChart (given that Helm v3 cannot force apply jobs), we'd need to render the chart in-memory, and check for jobs (or other resources with immutable fields).