erp5: Make mariadb data-directory parameterise.

stack/erp5/instance-mariadb.cfg.in

@@ -101,7 +101,8 @@ command = {{ parameter_dict['findutils-location'] }}/bin/find "${directory:maria
 ip = {{ ip }}
 port = {{ port }}
 socket = ${directory:run}/mariadb.sock
-data-directory = ${directory:mariadb-data}
+{% set data_directory = slapparameter_dict.get('data-directory', '${directory:mariadb-data}') -%}
+data-directory = {{ data_directory }}
 pid-file = ${directory:run}/mariadb.pid
 error-log = ${directory:log}/mariadb_error.log
 slow-query-log = ${directory:log}/mariadb_slowquery.log