Let the test mapping updater make commits and upload changes.

This will make it easier to run it on many crates and upload all of
the changes.  It puts the uploaded CLs in a topic to save resources.
If the script does not change a TEST_MAPPING, it does not upload
anything.

Test: Run on a subset of crates.
Change-Id: I47b4756d968c54d7d810c8a19a8a7419aebc6e15
1 file changed