Revert "[ConstraintSystem] Add skeleton of constraint optimizer"

This reverts commit b5f08a4.

Author: xedin

lib/Sema/CMakeLists.txt

@@ -13,7 +13,6 @@ add_swift_host_library(swiftSema STATIC
   CSStep.cpp
   CSTrail.cpp
   CSFix.cpp
-  CSOptimizer.cpp
   CSDiagnostics.cpp
   CodeSynthesis.cpp
   CodeSynthesisDistributedActor.cpp

lib/Sema/CSOptimizer.cpp

@@ -1823,8 +1823,6 @@ Constraint *ConstraintSystem::selectDisjunction() {
   if (disjunctions.empty())
     return nullptr;
 
-  optimizeDisjunctions(disjunctions);
-
   if (auto *disjunction = selectBestBindingDisjunction(*this, disjunctions))
     return disjunction;