Newsfeed Top/Latest #4998

Summary

Closes #4998 (closed)

Testing consideration

• set the experiments_id cookie to 1003764610978811918 for on and 1003764610978811919 for off variations
• top feed and the latest feed should load at the same time together.
• if the top feed fails to load for whatever reason, the latest feed should still be visible.
• clicking on the newsfeed should reload both feeds.
• changing feed should refresh the newsfeed
• entities that have been seen should not appear again in the top feeds

Estimated Regression Scope

• main newsfeed