Fix finalized artifacts for tethering in API 30

Due to a metalava bug at the time, many APIs had to be added to both
@SystemApi and @SystemApi(client = MODULE_LIBRARIES), which was also
persisted in the txt files. These were cleaned up from the HEAD txt
files in the change Ie1ad6711c490c679ebcfacd97154380a8810ba1c.

Clean up the prebuilt artifacts too, which simplifies adding more
compat checks for the finalized artifacts.

Bug: 174847574
Test: compat check (in a different CL) passes
Change-Id: I6a3ad1607b77534ea7e1effe74b5b665344bbaab
2 files changed