Breaking Change: Remove deprecated Arena::CreateMessage.

These have been marked ABSL_DEPRECATED as of v5.27.x and is replaced with Arena::Create which has been available since v3.0.0.

See https://engdoc.corp.google.com/eng/doc/devguide/proto/news/2024-10-02.md#arenacreatemessage

PiperOrigin-RevId: 689557672

src/google/protobuf/arena.h

@@ -197,19 +197,6 @@ class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
 
   inline ~Arena() = default;
 
-#ifndef PROTOBUF_FUTURE_REMOVE_CREATEMESSAGE
-  // Deprecated. Use Create<T> instead.
-  template <typename T, typename... Args>
-  ABSL_DEPRECATED("Use Create")
-  static T* CreateMessage(Arena* arena, Args&&... args) {
-    using Type = std::remove_const_t<T>;
-    static_assert(
-        is_arena_constructable<Type>::value,
-        "CreateMessage can only construct types that are ArenaConstructable");
-    return Create<Type>(arena, std::forward<Args>(args)...);
-  }
-#endif  // !PROTOBUF_FUTURE_REMOVE_CREATEMESSAGE
-
   // Allocates an object type T if the arena passed in is not nullptr;
   // otherwise, returns a heap-allocated object.
   template <typename T, typename... Args>

src/google/protobuf/port_def.inc

@@ -144,10 +144,6 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 // Owner: shaod@, gberg@
 #define PROTOBUF_FUTURE_DESCRIPTOR_EXTENSION_DECL 1
 
-// Removes Arena::CreateMessage, as Arena::Create is equivalent
-// Owner: ckennelly@, mkruskal@
-#define PROTOBUF_FUTURE_REMOVE_CREATEMESSAGE 1
-
 // Renames DescriptorPool::AddUnusedImportTrackFile
 // Owner: mkruskal@
 #define PROTOBUF_FUTURE_RENAME_ADD_UNUSED_IMPORT 1