Remove matthewb from OWNERS. BUG=None TEST=None Change-Id: I7deca2347b5968a0faf3222a9dbc8f57fc035b0d Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crostestutils/+/6174313 Commit-Queue: Keith Haddow <[email protected]> Tested-by: Keith Haddow <[email protected]> Reviewed-by: Garry Wang <[email protected]> Commit-Queue: Garry Wang <[email protected]> Auto-Submit: Keith Haddow <[email protected]>