Remove eugenebut from ios/chrome/browser/ui/download owners

Bug: None
Change-Id: Ibce50e2c29c55108f356f9af8e78c740e84f4c2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633197
Commit-Queue: Eugene But <eugenebut@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845712}

ios/chrome/browser/ui/download/OWNERS

-eugenebut@chromium.org
-sdefresne@chromium.org