Fix monkey event stream for pinch zoom

Previously, monkey left dangling pointers when injecting pinch-zoom.
This CL corrects the monkey event stream.

Also, now that ACTION_UP is a throttlable event, there is a
MonkeyThrottleEvent added at the end.

Bug: 281806933
Test: atest monkey_test
Change-Id: Id52ba3fbf7b5666498cacc8e9bd8ec8df9ca1cec
3 files changed