[ObjCARC] Use objc_msgSend instead of llvm.objc.msgSend in tests

D55348 replaced @objc_msgSend with @llvm.objc.msgSend in tests
together with many other objc intrinsics. However, this is not a
recognized objc intrinsic (https://llvm.org/docs/LangRef.html#objective-c-arc-runtime-intrinsics)
and does not receive special treatment by LLVM. It's likely that
uses of this function were renamed by accident.

This came up in D106013, because the address of @llvm.objs.msgSend
is taken, something which is normally not allowed for intrinsics.

Differential Revision: https://reviews.llvm.org/D106094