Disable "check last" for test api

@TestApi does not have stability requirements, so we shouldn't be
checking its compatibility with the last released version.

This CL removes the expectation that a test-removed.txt is checked in
for each module during finalization.

Bug: 155197156
Test: m (with SDK 30 imported)
Change-Id: Ib3f671493f1d230116bec51b884e8072643b10d4