Remove some duplicated code of transient launch

The inRecentsTransition is the same as isTransientHide, while the
latter might be a bit more efficient.

Also use asyncTraceForTrackBegin to make the trace display
in the same row of perfetto view.

Bug: 275508603
Test: CtsActivityManagerDeviceTestCases
Change-Id: I0326035a1c63cda1581cc017074983ecb05596bc