chore(backend): remove usage of deprecated commonLabels in Kustomize manifests

[etheleon]

Description of your changes:

Removed commonLabels since it's deprecated in Kustomize's api/v0.16.0 release. In it's place labels and selectors should be mentioned explicitly in the resource.

Checklist:

• You have signed off your commits
• The title for your pull request (PR) should follow our title convention. Learn more about the pull request title convention used in this repository.

[google-oss-prow]

Hi @etheleon. Thanks for your PR.

I'm waiting for a kubeflow member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign zijianjoy for approval. For more information see the Kubernetes Code Review Process.

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[etheleon]

resolves #11272

[etheleon]

running grep -r "commonLabels" does not return any file

[etheleon]

/verify-owners

[hbelmiro]

/ok-to-test
/rerun-all

[DharmitD]

@HumairAK could you approve the workflow runs? ty!

[etheleon]

hi @hbelmiro I've removed the redundant comments

[hbelmiro]

@etheleon can you please sign-off your commits?

[hbelmiro]

/ok-to-test
/rerun-all

[hbelmiro]

@etheleon did you had the chance to see my comments here?
#11289 (review)

[hbelmiro]

Thank you @etheleon.
You still need to sign off your commits.

[etheleon]

Thank you @etheleon. You still need to sign off your commits.

Let me rebase and sign off thanks for reminding

[hbelmiro]

/lgtm

cc @HumairAK