Adds current registry route hostname when generating the new certs

[jtudelag]

There are situations when docker-registry hostname is not "docker-registry-default." + {{ openshift_master_default_subdomain }}.

For example when a customer wants to give the Registry a prettier name, or when using Router sharding, labelling the default NS, and using a different subdomain than the default one.

The redeploy registry certs playbooks does not take that into account, so It will never add the current docker-registry route hostname to the certificates..

This PR fix that,

[openshift-ci-robot]

Hi @jtudelag. Thanks for your PR.

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[vrutkovs]

/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jtudelag, vrutkovs

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[vrutkovs]

/ok-to-test

[openshift-bot]

/retest

Please review the full test history for this PR and help us cut down flakes.