[web] Don't display current user in UserList

Summary:
ENG-2015
Current user shouldn't be displayed in UserLists (blocking/ sending friend request to yourself doesn't make sense),

Test Plan: Check if the current user is not visible in the block/ friend list and can't be searched for. Check if other users can still be selected.

Reviewers: tomek, atul, abosh, ginsu

Reviewed By: atul

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D5466