Remove obsolete references to IPCThreadState/ProcessState.

Threadpool can now be configured/joined if needed with
configureRpcThreadpool() / joinRpcThreadpool().

Bug: 31226656
Test: mma
Change-Id: I0d7d9924cc8c8851cc2b61ebdae906204909890e
(cherry picked from commit 028223775be7539c5b569a454524584a7ad8e152)
1 file changed