Update scheduler task names to new ones

Update scheduler task names related to the loading of origins to the new naming scheme (see swh-scheduler!96 (closed)).

Warning: The load-pypi task type has not been added to the production database. This should be done prior to any deployment.

Related swh-scheduler#1508 (closed)

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Migrated from D1490 (view on Phabricator)

swh/lister/core/lister_base.py

@@ -414,7 +414,7 @@ class SWHListerBase(abc.ABC, config.SWHConfig):
         Returns:
             the same information in a different form
         """
-        _type = 'origin-update-%s' % origin_type
+        _type = 'load-%s' % origin_type
         _policy = 'recurring'
         return utils.create_task_dict(_type, _policy, origin_url)