Allow period fallbacks on Discovery feeds

Testing

• Go to https://goal-top-algorithm-redux-2.minds.io/newsfeed/global/top;period=12h
• Check that the Posts older than 12H legend appears at some point, with older posts below
• Play around with TOP and LATEST filters.

Note: Do not use HOT as it's running on the old votes-per-period system which isn't running on Sandboxes.

Devs: Refreshing Top posts list

• Switch to Sandbox cluster
• $ kubectl get pods | grep goal-top-algorithm-redux-2-minds-app
• $ kubectl exec -ti goal-top-algorithm-redux-2-minds-app-{random_ID_HERE} sh
• $ cd /var/www/Minds/engine
• $ php cli.php top all sync_activity --metric=down --from=1 && php cli.php top all sync_activity --metric=up --from=1 && php cli.php top all sync_images --metric=down --from=1 && php cli.php top all sync_images --metric=up --from=1 && php cli.php top all sync_videos --metric=down --from=1 && php cli.php top all sync_videos --metric=up --from=1 && php cli.php top all sync_blogs --metric=down --from=1 && php cli.php top all sync_blogs --metric=up --from=1

Issues

• Closes #2269 (closed)