[Enhancement][opensearch] Allow user-defined labels on pvcs

[simonstumpf]

Is your feature request related to a problem? Please describe.
Our PVCs get backuped based on a policy defined in the PVC label. However it's currently not possible to define additional labels for the PVC (instead the global labels are applied if .Values.persistence.labels.enabled is true).
Describe the solution you'd like
I'd like to define additional labels that are added besides the global labels.

Describe alternatives you've considered
I don't see another way of doing it.

Additional context

[prudhvigodithi]

[Triage]
I see the PR #555 is already created for this change, thanks for your contribution @simonstumpf.

[peterzhuamazon]

Waiting for the backport to 1.x before closing this.

Thanks.

[simonstumpf]

@peterzhuamazon
Thanks!
Should I merge my branch into the 1.x branch or the main?

[prudhvigodithi]

Hey @simonstumpf please create a PR to 1.x branch.

[simonstumpf]

@prudhvigodithi Im a little bit confused. I've created the PR, but there are too many changes? Do you see what I did wrong?

[prudhvigodithi]

@simonstumpf you need to clone 1.x--> add your changes-->then please create the PR to 1.x.

[peterzhuamazon]

@prudhvigodithi Im a little bit confused. I've created the PR, but there are too many changes? Do you see what I did wrong?

Added steps here also closed that PR since it is messing up.
#599 (comment)

Thanks.

[peterzhuamazon]

Resolved, closing now.