api: remove set/get game drawing mode

This is being moved internally

runelite-client/src/main/java/net/runelite/client/ui/ClientPanel.java

@@ -29,7 +29,6 @@ import java.awt.BorderLayout;
 import java.awt.Color;
 import javax.annotation.Nullable;
 import javax.swing.JPanel;
-import net.runelite.api.Client;
 import net.runelite.api.Constants;
 
 final class ClientPanel extends JPanel
@@ -48,13 +47,5 @@ final class ClientPanel extends JPanel
 		}
 
 		add(client, BorderLayout.CENTER);
-
-		// This causes the whole game frame to be redrawn each frame instead
-		// of only the viewport, so we can hook to MainBufferProvider#draw
-		// and draw anywhere without it leaving artifacts
-		if (client instanceof Client)
-		{
-			((Client)client).setGameDrawingMode(2);
-		}
 	}
 }