production/storage: Migrate objstorage multiplexer to use banco rpc

Refs. swh/infra/sysadm-environment#5226

swh/values/production/default.yaml

@@ -331,7 +331,7 @@ multiplexerBancoSaamRemoteConfiguration:
   - cls: filtered
     storage_conf:
       cls: remote
-      url: http://banco.internal.softwareheritage.org:5003/
+      url: http://objstorage-ro-banco-xfs-rpc-ingress
     filters_conf:
     - type: readonly
   - cls: filtered