Fix race condition in PointerControllerTest

A previous CL ag/27261516 moved initialisation of thread before the
looper it uses. It introduced a race condition causing tests failures.
This CL changes order of initliation to ensure looper is always
initilised befor the thread.

Bug: 343818855
Test: atest libinputservice_test
Change-Id: Ibcb4d31be6a607f37eeee7207182cdd5eb1d7ead