feat: remove kf metadata server

[Bobgy]

Which issue is resolved by this Pull Request:
Part of kubeflow/metadata#250

Description of your changes:

Checklist:

• Unit tests have been rebuilt:
  1. cd manifests/tests
  2. make generate-changed-only
  3. make test

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[Bobgy]

/assign @Jeffwan @PatrickXYS @neuromage
I'm not sure we want to do this now, a problem is that when KF metadata UI virtual service is removed. I think users cannot access KF metadata server either, so I think there's no reason to keep metadata server too.

[PatrickXYS]

I think removal sounds reasonable since we have already removed metadata UI virtualservice.

SGTM

/cc @kubeflow/wg-notebook-leads

[Jeffwan]

@Bobgy @PatrickXYS I think it makes sense to remove all and only leave grpc deployment and server there. kubeflow/metadata#250

[Jeffwan]

/lgtm

[Jeffwan]

kubeflow/kubeflow#5404 PR to remove link in central dashboard