Celery: increase frequency of delete_closed_external_versions task (#10425)

* Celery: increase frequency of `delete_closed_external_versions` task

We have 255k versions that should have been deleted already, but we are
executing the task with a limit of 200 version. This makes the task to not catch
up with all the versions that has to delete, and we keep accumulating them.

This commit increases the frequency from "once a day" to "every 3 hours". It
will help to catch up and to keep our database clean of closed PRs.

Related readthedocs/readthedocs-ops#1291

* Update readthedocs/settings/base.py

Co-authored-by: Santos Gallegos <[email protected]>

---------

Co-authored-by: Santos Gallegos <[email protected]>

Author: humitos

readthedocs/settings/base.py

@@ -511,9 +511,11 @@ def TEMPLATES(self):
                 'delete': True,
             },
         },
-        'every-day-delete-inactive-external-versions': {
+        'every-three-hours-delete-inactive-external-versions': {
             'task': 'readthedocs.builds.tasks.delete_closed_external_versions',
-            'schedule': crontab(minute=0, hour=1),
+            # Increase the frequency because we have 255k closed versions and they keep growing.
+            # It's better to increase this frequency than the `limit=` of the task.
+            'schedule': crontab(minute=0, hour='*/3'),
             'options': {'queue': 'web'},
         },
         'every-day-resync-remote-repositories': {