[aapt2] Change the base timestamp of the traces

Perfetto UI doesn't work well if the timestamps are way into
the 64 bit territory. This CL ensures we always start with 0,
making the UI work well for all traces

Bug: 294025081
Test: manual tracing run
Change-Id: I5b74d4dda62ff40c1eab7e33144533e77e59c949
1 file changed