erp5: fixed mysql data import when we have stored routines

Issue was:
- user project_user was created
- project_user create stored routines
- mysql data is dumped (including list of users)
- mysql data is restored, but stored routines have the information
  DEFINER that must match an existing user. This does not
  work if there is no flush privileges instructions

So make sure to insert flush privileges while dumping

stack/erp5/instance-mariadb.cfg.in

@@ -107,7 +107,7 @@ time = {{ dumps(backup_periodicity) }}
 #   can be fully restored.
 # master-data: use value "2" as we are not in a replication case
 #}
-command = "${binary-wrap-mysqldump:wrapper-path}" -u root --all-databases --single-transaction {% if incremental_backup_retention_days > -1 %}--flush-logs --master-data=2 {% endif %}| {{ parameter_dict['gzip-location'] }}/bin/gzip > "${directory:mariadb-backup-full}/$({{ parameter_dict['coreutils-location'] }}/bin/date "+%Y%m%d%H%M%S").sql.gz"
+command = "${binary-wrap-mysqldump:wrapper-path}" -u root --all-databases --flush-privileges --single-transaction {% if incremental_backup_retention_days > -1 %}--flush-logs --master-data=2 {% endif %}| {{ parameter_dict['gzip-location'] }}/bin/gzip > "${directory:mariadb-backup-full}/$({{ parameter_dict['coreutils-location'] }}/bin/date "+%Y%m%d%H%M%S").sql.gz"
 {# KEEP GLOB PATTERN IN SYNC with generated filenames above
 #           YYYYmmddHHMMSS -#}
 file-glob = ??????????????.sql.gz