Remove scottmg@ from //build OWNERS

Not following chromium-dev or most dev in //build any more so there's
probably not many changes I'm qualified to review here any more.

Change-Id: Ie35015521eb18787c68b401c4ae5700ea3654f95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2244039
Auto-Submit: Scott Graham <scottmg@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Scott Graham <scottmg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#778006}

build/OWNERS

@@ -3,7 +3,6 @@ brucedawson@chromium.org
 dpranke@chromium.org
 dpranke@google.com
 jochen@chromium.org
-scottmg@chromium.org
 thakis@chromium.org
 thomasanderson@chromium.org
 tikuta@chromium.org