Enable NullAway presubmit check on chrome/android

Will check new files to ensure they are @NullMarked.

Bug: None
Change-Id: Icaa3a7bdb9b9682771f47779ede27c09f673209d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6576600
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1463609}

PRESUBMIT.py

@@ -7603,7 +7603,6 @@ def _CheckAndroidNullAwayAnnotatedClasses(input_api, output_api):
                     r'.*Test.*\.java',
                     r'^android_webview/.*',  # Temporary, crbug.com/389129271
                     r'^build/.*',
-                    r'^chrome/android/.*',  # Temporary, crbug.com/389129271
                     r'^chromecast/.*',
                     r'^components/cronet/.*',
                     r'^tools/.*',