Allow the monitoring IP whitelist to be specified for unicorn

Summary

Currently, there is no way to specify your own monitoring IP whitelist. In the latest charts in master, it is a hard-coded entry, like so:

monitoring:
  ip_whitelist:
    - 0.0.0.0/0

Steps to reproduce

Try to change the monitor IP whitelist as described here: https://docs.gitlab.com/ee/administration/monitoring/ip_whitelist.html

Configuration used

Default config will reproduce

Current behavior

There is no way to specify my own monitoring IP whitelist

Expected behavior

That I could restrict access to the monitoring endpoints using my own IP whitelist

Versions

• Chart: 2.0.3
• Platform:
  • Cloud: IBM Cloud
• Kubernetes: (kubectl version)
  • Client: v1.15.1
  • Server: v1.12.10+IKS
• Helm: (helm version)
  • Client: v2.14.2
  • Server: v2.14.1