hpb: rm MoveMessage as amigo

PiperOrigin-RevId: 754925277

Author: honglooker

hpb/backend/upb/interop.h

@@ -33,7 +33,7 @@ namespace hpb::interop::upb {
 // TODO: b/365824801 - consider rename to OwnMessage
 template <typename T>
 T MoveMessage(upb_Message* msg, upb_Arena* arena) {
-  return T(msg, arena);
+  return internal::PrivateAccess::InvokeConstructor<T>(msg, arena);
 }
 
 template <typename T>

hpb_generator/gen_messages.cc

@@ -267,8 +267,6 @@ void WriteModelPublicDeclaration(
         friend struct ::hpb::internal::PrivateAccess;
         friend Proxy;
         friend CProxy;
-        friend $0(hpb::interop::upb::MoveMessage<$0>(upb_Message* msg,
-                                                     upb_Arena* arena));
       )cc",
       ClassName(descriptor),
       upb::generator::CApiMessageType(descriptor->full_name()),