[clang][Apple][cmake] Disable plugin support at LLVM level (#89483)

Matches up with the clang setting

Author: cyndyishida

clang/cmake/caches/Apple-stage2.cmake

@@ -16,6 +16,7 @@ set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
 set(LLVM_ENABLE_MODULES ON CACHE BOOL "")
 set(LLVM_EXTERNALIZE_DEBUGINFO ON CACHE BOOL "")
 set(LLVM_ENABLE_EXPORTED_SYMBOLS_IN_EXECUTABLES OFF CACHE BOOL "")
+set(LLVM_PLUGIN_SUPPORT OFF CACHE BOOL "")
 set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
 set(CLANG_SPAWN_CC1 ON CACHE BOOL "")
 set(BUG_REPORT_URL "http://developer.apple.com/bugreporter/" CACHE STRING "")