Core/World: short circuit setWorldState and avoid a db query in case there's nothing to update really

(cherry picked from commit c7b8f0f773)

src/server/game/World/World.cpp

@@ -3431,6 +3431,9 @@ void World::setWorldState(uint32 index, uint32 value)
     WorldStatesMap::const_iterator it = m_worldstates.find(index);
     if (it != m_worldstates.end())
     {
+        if (it->second == value)
+            return;
+
         PreparedStatement* stmt = CharacterDatabase.GetPreparedStatement(CHAR_UPD_WORLDSTATE);
 
         stmt->setUInt32(0, uint32(value));