Revert "[SandboxVec] Add barebones Region class." (#109058)

Reverts #108899

It broke the llvm-clang-x86_64-win-fast buildbot.

Author: slackito

llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Region.h

@@ -5,7 +5,6 @@ add_llvm_component_library(LLVMVectorize
   LoopVectorize.cpp
   SandboxVectorizer/DependencyGraph.cpp
   SandboxVectorizer/Passes/BottomUpVec.cpp
-  SandboxVectorizer/Region.cpp
   SandboxVectorizer/SandboxVectorizer.cpp
   SLPVectorizer.cpp
   Vectorize.cpp

llvm/lib/Transforms/Vectorize/CMakeLists.txt

@@ -9,5 +9,4 @@ set(LLVM_LINK_COMPONENTS
 
 add_llvm_unittest(SandboxVectorizerTests
   DependencyGraphTest.cpp
-  RegionTest.cpp
   )