Remove LangId related code.

FYI: We have plans to reintroduce this in some form in the near future.

Fixes: 62571798
Fixes: 64096360

Test: bit FrameworksCoreTests:android.view.textclassifier.TextClassificationManagerTest
Change-Id: I864d6c1143af6a2485cabdfe85116b5922a3e315