Add some trace points to compaction batches and cancellation

Adding a few trace points that will help to shed some light into
some field traces that show long compaction running times to determine
whether cancellation is not properly working in the field or if the
batch sizes are too big.

Bug: 226463719
Test: Verified trace points in perfetto.
Change-Id: I362044a38ffc5e820b7fddf6cb08fa2325e6929b