PointerChoreographer: Remove ability to create mouse controllers OTF

In the following CL, we made a change that results in the mouse cursor
position being valid whenever there is a mouse or touchpad connected:
I55898a3de1beb0f83f5da199521f26a886fb596c

This means we are no longer depending on creating mouse controllers
on-the-fly based on the input events. Remove the logic that creates
mouse controllers on-the-fly.

Bug: 327717240
Test: atest inputflinger_tests
Change-Id: I0fa10ef48055d80136083a1c0ab23522f6683fdc