Event Timing: Treat Orphan Pointerup As Non-Interaction

* Previous undesired outcome: scrolling can be measured as an
  interaction.
* Root cause: event timing are getting an orphan pointerup event (no
  paired pointerdown) when issue reproduced, which triggers
  interactionId generation and become an interaction.
* This CL address it by: identifying orphan pointerup in event timing
  and skip interactionId generation.

Bug: 40935137
Change-Id: I005813f54e0f50edd43565871458bf98080d659a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5402056


Reviewed-by: Michal Mocny <mmocny@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Aoyuan Zuo <zuoaoyuan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1281237}