Temporarily Revert "[clangd] Add Random Forest runtime for code completion."

as a header doesn't appear to have made it into the commit.

This reverts commit 9b6765e and followup

Author: echristo

clang-tools-extra/clangd/CMakeLists.txt

@@ -28,9 +28,6 @@ set(LLVM_LINK_COMPONENTS
   FrontendOpenMP
   Option
   )
-  
-include(${CMAKE_CURRENT_SOURCE_DIR}/quality/CompletionModel.cmake)
-gen_decision_forest(${CMAKE_CURRENT_SOURCE_DIR}/quality/model CompletionModel clang::clangd::Example)
 
 if(MSVC AND NOT CLANG_CL)
  set_source_files_properties(CompileCommands.cpp PROPERTIES COMPILE_FLAGS -wd4130) # disables C4130: logical operation on address of string constant
@@ -80,7 +77,6 @@ add_clang_library(clangDaemon
   TUScheduler.cpp
   URI.cpp
   XRefs.cpp
-  ${CMAKE_CURRENT_BINARY_DIR}/CompletionModel.cpp
 
   index/Background.cpp
   index/BackgroundIndexLoader.cpp
@@ -121,11 +117,6 @@ add_clang_library(clangDaemon
   omp_gen
   )
 
-# Include generated CompletionModel headers.
-target_include_directories(clangDaemon PUBLIC
-  $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>
-)
-
 clang_target_link_libraries(clangDaemon
   PRIVATE
   clangAST