[stable/neo4j] make neo4j service definition more extensible

[javamonkey79]

Is your feature request related to a problem? Please describe.
As is right now, it is not possible to make the neo4j chart extensible, for example making it a load balancer, adding on additional pod annotations (useful for things such as external dns).

Describe the solution you'd like
I would like to see service type and additional service annotations added to the service definition (core-dns.yaml).

Describe alternatives you've considered
I don't think there are any alternatives.

Additional context
This blocks this issue amundsen-io/amundsen#327

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