No error should be thrown if input gesture file cannot be found

The input-gestures.xml file can be missing if input gestures have not
yet been configured by the user. No longer throw an error in this
case as it is a valid state.

Bug: 394929430
Test: Manually on device
Flag: EXEMPT bugfix
Change-Id: Ibd9a8516ef179157023918426cf2ced8aac15558