binderRpcTest: meet presubmit SLO time

Now, we only do all combinations with UNIX raw sockets, and
with the other socket types, we run tests in the most common
mode.

This may cause some issues to be missed, but it's required
to hit SLO for Android testing now.

Fixes: 292808096
Fixes: 292820454
Test: binderRpcTest (which is the slowest variant) takes about
    5 minutes now
Change-Id: I069e633f4fce34de431595af91a6cd91e89239fb