Add Rubin to override OWNERS file

Change-Id: I5c083896fa47f564627345707aae2cd8afb9682e
Test: N/A OWNERS change
Flag: TEST_ONLY

core/java/android/app/admin/EnterprisePlatform_OWNERS

 sandness@google.com #{LAST_RESORT_SUGGESTION}
-scottjonathan@google.com #{LAST_RESORT_SUGGESTION}
\ No newline at end of file
+scottjonathan@google.com #{LAST_RESORT_SUGGESTION}
+rubinxu@google.com #{LAST_RESORT_SUGGESTION}
\ No newline at end of file