GestureConverter_test: use Each matchers

This allows us to deduplicate matchers that are common to whole lists of
NotifyMotionArgs objects, making it much easier to identify the salient
parts of each sequence.

Bug: 245989146
Test: atest inputflinger_tests:GestureConverterTest \
            inputflinger_tests:GestureConverterTestWithChoreographer
Change-Id: I339cf484c64a829f0650759a2ced402139498562