StatefulSet not able to set custom labels

[alen-z]

Chart type
Memgraph Standalone

Chart version:
Latest.

What happened?
Not able to set custom StatefulSet resource labels. We depend on those. For example, other systems like Kyverno mutate resources based on configuration set in labels.

Environment:
Kubernetes.

Relevant log output:
No log, but easily traceable. StatefulSet points to helper to get the labels while helper does not exposes ability for user-defined labels.

[as51340]

@alen-z could you take a quick look at the PR to see if this would work for you?