Revert^2 "Add tranistion combine trace-events"

This reverts commit dcb7c268.

Reason for revert: add flag check

A common source of transition problems is when
multiple independent actions get combined into a
single transition.

This tries to add some trace events (and logs) around
these situations to help with identifying hotspots and
debugging.

Bug: 325114242
Test: Existing tests, just adding trace.
Flag: com.android.window.flags.transit_tracker_plumbing
Change-Id: I105e2e1fe49f7f1f570962582c6c1687906387dd