With the editing personalized slides, a user can see old persisted year in review reports from a previous username. We should clear out this slide if a user logs out, and allow it to be refetched and recalculated if they log in again.

Steps to reproduce

• Log-in with a test account (account #1) you know has edits
• Observe account #1's edit count on Year in Review
• Log out
• Log into another account (account #2, I have one with 0 edits)
• Observe the edit count is still for account #1

Reference: iOS Task T378135: [S] Clear out persisted personalized editing data upon logout