[iOS] Removing bzanotti from sign-in code

bzanotti no longer works in Chrome sign-in team.

Change-Id: I6c6b2e73599c5cc4340d2283059db9b3d2909ccb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2024892
Auto-Submit: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736015}

ios/chrome/browser/first_run/OWNERS

-bzanotti@chromium.org
+jlebel@chromium.org
 msarda@chromium.org
 
 # COMPONENT: UI>Browser>FirstRun

ios/chrome/browser/ui/authentication/OWNERS

-bzanotti@chromium.org
 jlebel@chromium.org
 msarda@chromium.org
 

ios/chrome/browser/ui/signin_interaction/OWNERS

-bzanotti@chromium.org
 jlebel@chromium.org
 msarda@chromium.org