Fixes broken v1.3 OIDC auth manifest

[berndverst]

v1.3 OIDC auth manifests are broken

Example installation of Kubeflow v1.3 using kustomize provided by @yanniszark does not succeed as a result

Which issue is resolved by this Pull Request:
Corrects #1735

Description of your changes:
Current OIDC Auth Service manifests are not valid. This addresses the syntax error.

Current error:

kustomize build --load_restrictor=none common/oidc-authservice/base
Error: json: unknown field "env"

Checklist:

• Unit tests pass:
  Make sure you have installed kustomize == 3.2.1
  1. make generate-changed-only
  2. make test

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[berndverst]

@yanniszark this will need to be cherry-picked into the v1.3-branch FYI

[davidspek]

Duplicate of #1789

[yanniszark]

@berndverst thanks for the PR! In general, I'm in favor of using the newer envs field, however I don't think:

Example installation of Kubeflow v1.3 using kustomize provided by @yanniszark does not succeed as a result

is accurate. Kustomize 3.2.0, which is explicitly provided by the installation guide, builds the installation successfully.
Since @davidspek has already opened #1789, I'm closing this as a duplicate and continuing there.