libbinder: RPC drop extra header info

A lot of the data written in interface tokens (work source, strict mode,
etc..) doesn't make sense in the context of RPC calls. Also, we don't
want to freeze this part of the wire protocol.

Bug: 167966510
Test: binderRpcTest
Change-Id: I5c0bb923d1d4c2a4ffa49b117dbed16bce0a1c20