FIX: Truncate badge timestamps derived from non-public data (PR #12882)

Link shares are truncated to the top of the hour, and flagging is truncated to the beginning of the month.

Test failures in UsersController#perform_account_activation and User.enqueue_welcome_message happen on master


I dunno, I don’t really buy that this adds that much more security here. if you are getting 1 flag per month this adds almost no protection.

I was flagged → look at first flag badge … ah this new user flagged me.