Jira: OSPRH-16628

Adds end-to-end support for consuming Keystone Application Credentials (AppCred) in the telemetry-operator, enabling Ceilometer, Aodh, and CloudKitty pods to use AppCred-based authentication when available.

API changes:

Adds an optional auth field to telemetry service CRs:

• spec.auth.applicationCredentialSecret — name of the Secret that contains the Keystone Application Credential ID and Secret (AC_ID and AC_SECRET).

This is added for:

• Ceilometer CRs
• Aodh CRs
• CloudKitty CRs (and the related API/Proc CRs where applicable)

Reconcile behavior:

• Reads spec.auth.applicationCredentialSecret
• Attempts to load AC_ID / AC_SECRET from the referenced Secret (via the Keystone helper)
• If the Secret is missing or incomplete, reconciliation falls back to password authentication (AppCred auth is optional and not treated as an error)

Once the AppCred Secret is ready with valid AC_ID / AC_SECRET:

• Templates AppCred credentials into the generated service configuration (e.g. ceilometer.conf, aodh.conf, cloudkitty.conf)

• The rendered config hash naturally includes AppCred values, triggering rolling updates when credentials rotate

• All controllers use the same service user’s AppCred Secret for their respective service (ceilometer/aodh/cloudkitty)

• Updates Keystone auth sections to support AppCred with a block-based if/else structure:

  • AppCred: auth_type = v3applicationcredential + application_credential_id + application_credential_secret
  • Else: existing password-based auth

Depends-on: openstack-k8s-operators/keystone-operator#567