Chart: configurable enableServiceLinks

[johanjk]

Chart support EnableServiceLinks

EnableServiceLinks is a source of subtle bugs, it introduces env vars that can conflict with user env vars etc.
It's also noisy, pollutes the env, and increase pod startup time.
Make it configurable in the chart, and default to false

It is open for debate if the default should stay true, as some users might technically rely on it existing.
Hence it can be seen as a breaking change. I am open to keeping the default true.

Testing

Tested with helm template chart for enableServiceLinks: true/false.

Current workaround

postRenders:
  - kustomize:
      patches:
        - target:
            version: v1
            kind: Deployment
          patch: |
            - op: add
              path: /spec/template/spec/enableServiceLinks
              value: false
        - target:
            version: v1
            kind: CronJob
          patch: |
            - op: add
              path: /spec/jobTemplate/spec/template/spec/enableServiceLinks
              value: false

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[jscheffl]

I'd be OK with this change and also with the change of default. But I'd like other voices as well as this might be a change in behavior if you upgrade. So putting this into Chart 2.0 (only)?

In this case as it is a behavioral change, would request to add a short newsfragment.