Summary:
Proxygen no longer uses `fbcode_builder` to run its tests, so whatever the purpose of D17158685, these `fbcode_builder` configs no longer affect Proxygen, and can be reverted to their original state.

Since the general design pattern for `fbcode_builder` has been to link everything as `.so`s, let's return to this (which helps fix Bistro's build).

Also, let's not waste time building & linking tests for libraries that are not the library under test. That is:
 - Before: The Bistro build also builds tests for wangle, proxygen, etc. This is a result of some accidental changes in D17158685.
 - After: We explicitly don't build test for any of the 4 dependencies here. This is OK because each project also has its own `fbcode_builder_config.py`, which **does** build tests.

This latter part should result in a build-time reduction.

Reviewed By: lnicco

Differential Revision: D17819858

fbshipit-source-id: 7cad1bed86b2f0c3934b0fc5d6fb33e6a2ee2695