tests: Remove input driver tests

libinput is the way forward which has its own testsuite. Thus it does no
longer make sense to test other input drivers. For input during other
tests we have the inputtest driver.

The current tests for input drivers are unreliable and effectively
unfixable, because of the race condition introduced by separate input
thread. The inputtest driver has the required synchronization
3 jobs for remove-useless-tests in 1 minute and 50 seconds