Add a mode to always translate with and without region translator
This is intended to eliminate (from measurements, not real life) the
potential overhead of the tracelet region selector. When active, non-Optimize
translations will go through the full translation process with
Translator::analyze and the tracelet region selector, only registering the
results of one of the two in SrcDB.
Reviewed By: @ottoni
Differential Revision: D1264288