[builtin][NFC] Remove ClangBuiltin<"__builtin_allow_ubsan_check"> (#87581)

We don't need clang builtin for this one.

It was copy pasted from `__builtin_allow_runtime_check`

RFC:
https://discourse.llvm.org/t/rfc-add-llvm-experimental-hot-intrinsic-or-llvm-hot/77641

Author: vitalybuka

llvm/include/llvm/IR/Intrinsics.td

@@ -1733,8 +1733,7 @@ def int_ubsantrap : Intrinsic<[], [llvm_i8_ty],
 
 // Return true if ubsan check is allowed.
 def int_allow_ubsan_check : DefaultAttrsIntrinsic<[llvm_i1_ty], [llvm_i8_ty],
-    [IntrInaccessibleMemOnly, IntrWriteMem, ImmArg<ArgIndex<0>>, NoUndef<RetIndex>]>,
-    ClangBuiltin<"__builtin_allow_ubsan_check">;
+    [IntrInaccessibleMemOnly, IntrWriteMem, ImmArg<ArgIndex<0>>, NoUndef<RetIndex>]>;
 
 // Return true if runtime check is allowed.
 def int_allow_runtime_check : DefaultAttrsIntrinsic<[llvm_i1_ty], [llvm_metadata_ty],