[Enhancement][data-prepper] add annotations for data-prepper service

[vasili439]

Is your feature request related to a problem? Please describe.
It's more related to security problem. I don't want to expose data-prepper service with AWS External LB but want to add annotation to create internal LB

Describe the solution you'd like
add

  {{- with .Values.service.annotations }}
  annotations:
    {{- toYaml . | nindent 4 }}
  {{- end }}

to templates/service.yaml

Describe alternatives you've considered
no

[gaiksaya]

[Triage]

Thanks for opening the issue. Please feel free to contribute until we get there.