Clean up binder txn tracking special case

Previously, binder txns were only traced for txns from sysui/launcher
to system_server.

ag/Iffc4bb534d239c07d2e4d43ab43a9ed76abe7496 enabled binder txn tracking
more broadly

Removed the special case for sysui/launcher and cleaned up the code

Test: Manual
Bug: 161393989
Change-Id: I9d46d2362ca0ca33bc2477d68092f7ba5fe9c8ac