Use WATCH mode for config reload sidecar

[quilicicf]

Is your feature request related to a problem? Please describe

I've got a Jenkins instance with a pretty big number of jobs.
I've hit the K8s limit on ConfigMap size (1MB), meaning that I had to split my configuration in multiple ConfigMaps.
The problem arises when I delete a ConfigMap.
Since the K8s sidecar is configured to use the METHOD SLEEP, it can't delete the associated file in the Jenkins PVC (probably because of this bug?).

Describe the solution you'd like

From what I understand of the issue, it should be fixed by setting the METHOD to WATCH instead of SLEEP but since I'm not sure why this is not the case currently, I'm not sure it is a good fix.

It looks like watching the ConfigMaps to apply the changes immediately would be desirable to me, maybe I'm not seeing the constraint that led to choosing SLEEP instead?

Would you consider either:

• changing the default method to WATCH
• or making it configurable via the Values?

Describe alternatives you've considered

I currently remove the config file manually via kubectl but it encourages bad security practices (needlessly elevated privileges, non-CasC-management...).

Additional context

I can open a PR with whatever solution you decide on.