Send 'admin emails' weekly, not daily

Daily seems to be to spammy, so let's default to weekly instead.

config/gitlab.yml.example

@@ -168,9 +168,9 @@ production: &base
     # once per hour you will have concurrent 'git fsck' jobs.
     repository_check_worker:
       cron: "20 * * * *"
-    # Send admin emails once a day
+    # Send admin emails once a week
     admin_email_worker:
-      cron: "0 0 * * *"
+      cron: "0 0 * * 0"
 
     # Remove outdated repository archives
     repository_archive_cache_worker:

config/initializers/1_settings.rb

@@ -245,7 +245,7 @@ Settings.cron_jobs['repository_check_worker'] ||= Settingslogic.new({})
 Settings.cron_jobs['repository_check_worker']['cron'] ||= '20 * * * *'
 Settings.cron_jobs['repository_check_worker']['job_class'] = 'RepositoryCheck::BatchWorker'
 Settings.cron_jobs['admin_email_worker'] ||= Settingslogic.new({})
-Settings.cron_jobs['admin_email_worker']['cron'] ||= '0 0 * * *'
+Settings.cron_jobs['admin_email_worker']['cron'] ||= '0 0 * * 0'
 Settings.cron_jobs['admin_email_worker']['job_class'] = 'AdminEmailWorker'
 Settings.cron_jobs['repository_archive_cache_worker'] ||= Settingslogic.new({})
 Settings.cron_jobs['repository_archive_cache_worker']['cron'] ||= '0 * * * *'