[grafana] Allow sc-alert to run both as init and watcher

[jgournet]

No description provided.

[jgournet]

@zanhsieh : sorry, I re-created a new PR as DCO failed and there were too many conflicts

[zanhsieh]

@jgournet Can you link the previous PR in this PR description so the maintainers can easily look up / review?

[jgournet]

Link to previous (same) PR: #3246

[jgournet]

@zanhsieh :
the merge was blocked because of a conflict on Chart.yaml version number.
I resolved the merge conflict, but we're back at waiting for all tests - hopefully you can resolve this again ?

thank you

[jkroepke]

@zanhsieh What did you think about the native sidecar feature in Kubernetes where the initContainer stay alive?

https://kubernetes.io/docs/concepts/workloads/pods/sidecar-containers/

I would appreciate that direction more than this PR.

[zanhsieh]

@jkroepke
I would keep backward compatibility by default and leave the users adapts themselves since I don't find helm having any solid way to detect new feature gates enabled in helm.