mariadb: the deprecated backup CronJob reads a root password Secret that is never created #4045

The deprecated backup.* CronJob in packages/apps/mariadb/templates/backup-cronjob.yaml reads MYSQL_PWD from a Secret that does not exist:

secretKeyRef:
  name: {{ .Release.Name }}
  key: root-password

The chart renders the credentials into {{ .Release.Name }}-credentials (templates/secret.yaml) and points the MariaDB CR at it with rootPasswordSecretKeyRef: {name: <release>-credentials, key: root}; neither the chart nor mariadb-operator creates a Secret named <release>. Every backup pod therefore sits in CreateContainerConfigError and no scheduled dump has run on this path since the credentials layout changed. The values.yaml comment keeps the block for backward compatibility and points new deployments at the operator-native backup strategy.

Two ways out, and the choice is a product decision rather than a code one: fix the reference (<release>-credentials / root), which silently starts scheduled dumps on every instance that still has backup.enabled set; or remove the CronJob path and fail loudly when backup.enabled is set, pointing at the operator-native path. Leaving it as it is means a setting that reads as working and does nothing.