Revert "Reapply "[Clang][CMake] Use IRPGO instead of FE PGO for Cmake Caches … (llvm#160133)"

This reverts commit 6f64b01.

This breaks two BOLT buildbots using this cache:
1. https://lab.llvm.org/staging/#/builders/126/builds/2760
2. https://lab.llvm.org/buildbot/#/builders/113/builds/8571

More investigation needed, so reverting for now.

Author: boomanaiden154

clang/cmake/caches/PGO.cmake

@@ -5,7 +5,7 @@ set(LLVM_ENABLE_PROJECTS "clang;lld" CACHE STRING "")
 set(LLVM_ENABLE_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind" CACHE STRING "")
 
 set(LLVM_TARGETS_TO_BUILD Native CACHE STRING "")
-set(BOOTSTRAP_LLVM_BUILD_INSTRUMENTED IR CACHE BOOL "")
+set(BOOTSTRAP_LLVM_BUILD_INSTRUMENTED ON CACHE BOOL "")
 set(CLANG_BOOTSTRAP_TARGETS
   generate-profdata
   stage2