swh.lister.gitlab: Use one configuration for the gitlab lister

Related T989

swh/lister/gitlab/lister.py

@@ -22,6 +22,14 @@ class GitLabLister(SWHIndexingHttpLister):
     # (method disable_deleted_repo_tasks)
     MODEL = GitLabModel
 
+    @property
+    def CONFIG_BASE_FILENAME(self):
+        """One gitlab lister for all instances.  We discriminate between the
+        origin on a per instance basis in the table.
+
+        """
+        return 'lister-gitlab'
+
     @property
     def ADDITIONAL_CONFIG(self):
         """Override additional config as the 'credentials' structure change
@@ -32,7 +40,7 @@ class GitLabLister(SWHIndexingHttpLister):
         """
         return {
             'lister_db_url':
-                ('str', 'postgresql:///lister-%s' % self.lister_name),
+                ('str', 'postgresql:///lister-gitlab'),
             'credentials':  # credentials is a dict
                 ('dict', {}),
             'cache_responses':