Change instrumentation sendKeyDownUp to send correct downtime

The downtime sent in the key event for ACTION_UP should match the
downtime for the ACTION_DOWN key event.

During refactoring, changes were made for gesture detection to
rely on upEvent.getDownTime() instead of the save "down time" from
the last ACTION_DOWN event which led to some tests starting to fail
that used instumentation to create "fake" events.
Refactoring CL: ag/33546967

Bug: 417770153
Test: Presubmit
Flag: EXEMPT test_only
Change-Id: Ib287aee6b7651d79def52146d479aa4da8aadb8a