Remove eugenebut from ios/chrome/browser/app_launcher owners

Bug: None
Change-Id: I8f127a795c5a457802ed89482b471f23a8ade6b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2634308
Auto-Submit: Eugene But <eugenebut@chromium.org>
Reviewed-by: Mohammad Refaat <mrefaat@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845225}

ios/chrome/browser/app_launcher/OWNERS

-eugenebut@chromium.org
 mrefaat@chromium.org