refactor(Core): remove unused imports (#9969)

src/server/game/Entities/Creature/Creature.cpp

@@ -48,7 +48,6 @@
 #include "WaypointMovementGenerator.h"
 #include "World.h"
 #include "WorldPacket.h"
-#include "Pet.h"
 
 // TODO: this import is not necessary for compilation and marked as unused by the IDE
 //  however, for some reasons removing it would cause a damn linking issue

src/server/game/Entities/Pet/Pet.cpp

@@ -17,7 +17,6 @@
 
 #include "Pet.h"
 #include "ArenaSpectator.h"
-#include "Battleground.h"
 #include "Common.h"
 #include "CreatureAI.h"
 #include "DatabaseEnv.h"

src/server/game/Entities/Player/Player.cpp

@@ -80,7 +80,6 @@
 #include "Util.h"
 #include "Vehicle.h"
 #include "Weather.h"
-#include "WeatherMgr.h"
 #include "World.h"
 #include "WorldPacket.h"
 #include "WorldSession.h"