controller: reset field managers for v2beta1

[hiddeco]

Fix: fluxcd/flux2#4479

[stefanprodan]

LGTM

Thanks @hiddeco I've tested this on Kubernetes 1.29.0 and after the upgrade a force reconcile is no longer needed.

The requirement is to bump the apiVersion and to add an annotation or change an existing field in spec e.g. interval to force the Kubernetes API to move the HelmRelease field managers to v2beta2.

Example:

apiVersion: helm.toolkit.fluxcd.io/v2beta2 # <- bump from v2beta1
kind: HelmRelease
metadata:
  annotations:
    fluxcd.io/upgradeTo: "v2beta2" # <- add annotation