Add components/sync/OWNERS to remaining Java Sync owners

Turns out the previous crrev.com/c/1402889 missed not one, but two
owners files...

Bug: none
Change-Id: I609ca114a08c1ac811ff8503d2d3e976c71acf1a
Reviewed-on: https://chromium-review.googlesource.com/c/1406994Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621998}

chrome/android/sync_shell/OWNERS

-mastiz@chromium.org
+file://components/sync/OWNERS
+
 nyquist@chromium.org
 yfriedman@chromium.org
 

chrome/test/android/javatests/src/org/chromium/chrome/test/util/browser/sync/OWNERS

-mastiz@chromium.org
+file://components/sync/OWNERS
+
 nyquist@chromium.org
 yfriedman@chromium.org