TouchInputMapper: remove PointerUsage code

The flag for this has now launched, so we're free to remove it, along
with a massive swath of code that it guarded, including the old touchpad
stack.

Test: $ atest --host inputflinger_tests
Fixes: 417466501
Bug: 281840344
Bug: 257078296
Flag: EXEMPT removing
      com.android.input.flags.disable_touch_input_mapper_pointer_usage
Change-Id: I6be262b8e9272d4ccb4777ce0954886e60fd5c5d
7 files changed