Fix shell-transit to legacy app-cancel metrics

When it performs a no-op, it should notify metrics-logger of
activity launch cancellations. Was blindly reporting everything
to start, now just report visible stuff.

This also fixes a problem during teardown where transition
collection wasn't waiting for pending pause.

Bug: 183993924
Test: atest ActivityMetricsLoggerTests
Change-Id: Ie0d4aea89b7e32744fdbd56a39d6266154015d32