Remove AchievementManager ChangeDisc call from Eject

This was causing the achievement runtime to shutdown in the middle
of a disc change even if the resulting disc was valid, which was
causing achievements like the ones in Resident Evil for completing
the entire game in a single session to break midway through.

Also adds a log to notify the user when the disc change is invalid
(e.g. different game inserted).

Source/Core/Core/AchievementManager.cpp

@@ -168,6 +168,8 @@ void AchievementManager::LoadGame(const DiscIO::Volume* volume)
     WARN_LOG_FMT(ACHIEVEMENTS, "Software format unsupported by AchievementManager.");
     if (rc_client_get_game_info(m_client))
     {
+      OSD::AddMessage("Unsupported media change; disabling achievements.", OSD::Duration::VERY_LONG,
+                      OSD::Color::RED);
       CloseGame();
     }
     else

Source/Core/Core/HW/DVD/DVDInterface.cpp

@@ -442,7 +442,6 @@ void DVDInterface::AutoChangeDiscCallback(Core::System& system, u64 userdata, s6
 
 void DVDInterface::EjectDiscCallback(Core::System& system, u64 userdata, s64 cyclesLate)
 {
-  AchievementManager::GetInstance().ChangeDisc(nullptr);
   system.GetDVDInterface().SetDisc(nullptr, {});
 }