rootdev: remove xiaochu@ from OWNERS He's left the team. BUG=chromium:995893 TEST=None Change-Id: I2909e5ee4e4cf128c05659314d5c0ae7e0bb84a2 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/rootdev/+/2001410 Tested-by: Nicolas Norvez <[email protected]> Auto-Submit: Nicolas Norvez <[email protected]> Reviewed-by: Benjamin Gordon <[email protected]> Commit-Queue: Nicolas Norvez <[email protected]>