machine_learning: add two new owners

Add another two owners who come form the same team and are also
primarily working on mlservice in CrOS.

BUG=none
TEST=no need for test

Change-Id: If299a76ae10a50ed1a58edf7f02b7b34bcde3a06
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2308614Reviewed-by: Andrew Moylan <amoylan@chromium.org>
Commit-Queue: Andrew Moylan <amoylan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791697}

chromeos/services/machine_learning/OWNERS

+alanlxl@chromium.org
 amoylan@chromium.org
+honglinyu@chromium.org
 martis@chromium.org
 # COMPONENT: UI>ML>Service