[chart/redis-ha][REQUEST] Support custom pod annotations on the service-test pod

[bengadbois]

Is your feature request related to a problem? Please describe.
The redis-ha test pod doesn't support custom pod annotations. For certain environments that may be needed.

Describe the solution you'd like
Most of the other deployments/statefulsets in redis-ha support the custom annotations, via .Values.podAnnotations. It would be useful to let the redis-ha test pod to also get custom annotations in a similar way.

Describe alternatives you've considered
My workaround until a fix is merged/released is to patch the test pod's .metadata.annotations. Somewhat inelegant, but works.

Additional context
The one potential risk here is users who previously set podAnnotations in their helm chart may be surprised when that annotation which previously didn't get set on the test pod now does. Since it's an annotation, not a label, it seems likely to introduce selector-based bugs like accidentally getting included as a target in a PDB.