Add application credential finalizer management

[Deydra71]

Jira: OSPRH-27509

Application Credential dev-doc: https://github.com/openstack-k8s-operators/dev-docs/blob/main/application_credentials.md

• Tracks the active AC secret name in Status.ApplicationCredentialSecret
• Add openstack.org/cinder-ac-consumer finalizer to the AC secret after service config is rendered
• On AC rotation, move the finalizer from the old secret to the new one
• On CR deletion, remove the consumer finalizer from the AC secret before cleaning up the CR

This ensures that the keystone-operator cannot revoke a rotated AC secret while Cinder is still consuming it.

Depends-On: openstack-k8s-operators/keystone-operator#685

Assisted-by: Claude Opus 4.6 noreply@anthropic.com

[openshift-ci]

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❌ openstack-k8s-operators-content-provider FAILURE in 18m 19s
⚠️ cinder-operator-kuttl SKIPPED Skipped due to failed job openstack-k8s-operators-content-provider
⚠️ cinder-operator-tempest SKIPPED Skipped due to failed job openstack-k8s-operators-content-provider

[openshift-ci]

PR needs rebase.

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