Revert "input: remove TouchInputMapper pointer usage flag"

This reverts commit 220fc417cb55b78bf69abea729b2a2384fdc3715.

Reason for revert: it causes small changes in the input event stream for
drawing tablets and absolute mice, which don't affect compatibility but
cause failures when the cleaned-up TouchInputMapper is tested against
the old CTS tests.

Reverted changes: /q/submissionid:33669427-remove-touchpad-stack-flag

Bug: 420320431
Test: $ atest CtsInputTestCases
Flag: TEST_ONLY
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:ece74c6f6149d7abfd67646d519100cfb6d535a6)
Merged-In: If2062190df8fa00b5c6c6016c6a0a685307e6b0f
Change-Id: If2062190df8fa00b5c6c6016c6a0a685307e6b0f