Remove huangml@ from OWNERS files

Bug: None
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ia9b7794733fef726c08e40cafed69e1672b071ab
Reviewed-on: https://chromium-review.googlesource.com/1079811Reviewed-by: Eugene But <eugenebut@chromium.org>
Reviewed-by: Shenghua Zhang <shenghuazhang@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Menglu Huang <huangml@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563146}

ios/build/bots/OWNERS

-huangml@chromium.org
 justincohen@chromium.org
 kkhorimoto@chromium.org
 rohitrao@chromium.org

ios/chrome/test/OWNERS

-huangml@chromium.org
 shenghuazhang@chromium.org
 eugenebut@chromium.org
 

ios/chrome/test/earl_grey/OWNERS

-huangml@chromium.org
 shenghuazhang@chromium.org
 eugenebut@chromium.org
 

ios/testing/earl_grey/OWNERS

-huangml@chromium.org
 shenghuazhang@chromium.org
 eugenebut@chromium.org
 

ios/third_party/earl_grey/OWNERS

-huangml@chromium.org
 justincohen@chromium.org
 rohitrao@chromium.org
 

ios/third_party/fishhook/OWNERS

-huangml@chromium.org
 justincohen@chromium.org
 rohitrao@chromium.org
 

ios/third_party/ochamcrest/OWNERS

-huangml@chromium.org
 justincohen@chromium.org
 rohitrao@chromium.org