Move shared partner customizations test code into the correct folder.
Test code that's used downstream needs to live in
chrome/test/android/javatests (which is included in the
chrome_java_test_support target), not chrome/android/javatests (which is
included only in the chrome_shell_test_apk target).
BUG=
444675
Committed:
https://crrev.com/5d49353ab0c34c986026fe5dca8b60e5e98999f9
Cr-Commit-Position: refs/heads/master@{#311530}