Fix input scenario detection in Performance Manager

The existing logic results in the InputScenarioObserver state getting
"stuck" in for example Tap scenario (the same can happen with typing).
The unit test added in this CL reproduces the issue, and it fails
without the corresponding code changes - crrev.com/c/6596977

The issues develops like this:

1. Tap starts, tap timeout timer also starts. The global counter goes to
1, the observers are notified.

2. Scroll starts. The timer has not expired yet (assuming that #2
happens very shortly after #1), and the timer is reset. The global
counter goes to 2, the global observers are not notified. This is
already a bug, but this isn't the worst thing.

3. Scroll ends => the timer is cancelled. The global counter goes down
to 1, the observers are again not notified.

4. There's no inactivity timer running in FrameInputStateDecorator, so
we're stuck in the tap state on the InputScenarioObserver side.

The new logic correctly terminates the lower priority input scenario. In
the example above it would notify all observers about Scroll in #2, and
then notify for no input in #3 as expected. Then it would proceed to
responding to any new input state upon new input events.

Bug: 406800559
Change-Id: I363b6a517a06d0a71c42cd59c45899a995c32f85
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6596750
Commit-Queue: Igor Kraskevich <kraskevich@google.com>
Reviewed-by: Joe Mason <joenotcharles@google.com>
Cr-Commit-Position: refs/heads/main@{#1469282}