Add TEST_MAPPING to textclassifier

Setup presubmit for textclassifier by using TEST_MAPPING.
We will get a dashboard for the test result as well.

Also fixed a few broken tests found by this CL.

BUG: 124041915

Test: atest --test-mapping frameworks/base/core/java/android/service/textclassifier/TEST_MAPPING

Change-Id: I0c516ea8699d7e94cfabd2ea98ebad58505c7e90