Remove Helm-related labels and annotations before reconciliation

Summary

Context: gitlab-org/charts/gitlab!2372 (comment 831377446)

With the deprecated Operator, we would skip Helm-related labels/annotations when global.operator.enabled=true.

With our new Operator, we don't set global.operator.enabled at all, meaning we end up with Helm-related labels and annotations. To avoid confusion and potential undesired behavior, we should consider removing those items before reconciling the objects.

Acceptance criteria

• Helm-related labels/annotations are removed prior to reconciliation