Revert "[keyserver/lib/web/native] fetch user avatar column from users table for remaning user fetchers"

Summary: This reverts commit 126db3bda66c39bac09f4f71957097a114521527.

Test Plan: n/a accidently hit the push button on my code editor

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D7158