Empty string for "owner_*" dimensions in all metrics.

[pawcykca]

What this PR does / why we need it:
Replace "" with empty string for "owner_kind", "owner_name" and "owner_is_controller" dimensions for all metrics.

How does this change affect the cardinality of KSM: (increases, decreases or does not change cardinality)
Does not change cardinality.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1919

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: pawcykca / name: Paweł Kubica (2c3ea01, 0553bf4, 9858387)

[k8s-ci-robot]

@pawcykca: This issue is currently awaiting triage.

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[pawcykca]

/easycla

[mrueg]

I believe easycla is failing because it does not recognize the email in https://github.com/kubernetes/kube-state-metrics/pull/1923/commits/2c3ea01cb2c2ca3fa6ea9958d899f497ef14f5c0.patch ?

[pawcykca]

/easycla

[mrueg]

/lgtm
/hold
For others to have a look

[dgrisonnet]

Thanks @pawcykca!

/lgtm
/unhold

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dgrisonnet, mrueg, pawcykca

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