[MariaDB] Allow for stable upgrades

Using a random bootstrap filename means any upgrade (even without
changes) causes MariaDB to churn and restart.

Change-Id: Ieaf577e413f8d672d24bf42c90b6110b52e542f0

mariadb/templates/statefulset.yaml

@@ -81,7 +81,7 @@ spec:
             - name: FORCE_RECOVERY
               value: {{ .Values.force_recovey | quote }}
             - name: BOOTSTRAP_FILE
-              value: {{ printf "/tmp/%s.sql" (randAlphaNum 8) }}
+              value: "/tmp/bootstrap.sql"
             - name: MARIADB_REPLICAS
               value: {{ .Values.pod.replicas.server | quote }}
             - name: WSREP_PORT