Add Mainline Test Mapping in libtextclassifier. am: 5be296072a am: 5b3cec7fdb

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libtextclassifier/+/14733423

Change-Id: Ic3d584a1c4f4f7d44259532f413f3abf526fe0ef