Fix Zalcano damage overlay to only show during Zalcano

This varp is for the hp hud, and applies to more content than just
Zalcano, so verify that the hp hud is for Zalcano

runelite-api/src/main/java/net/runelite/api/VarPlayer.java

@@ -188,11 +188,9 @@ public enum VarPlayer
 	MOUSE_BUTTONS(170),
 
 	/**
-	 * Zalcano's form
-	 * -1 : Player is outside or Zalcano is dead i.e. there's no healthbar to show
-	 * Anything else : The {@link NpcID} of the current form
+	 * {@link NpcID} for the HP HUD
 	 */
-	ZALCANO_FORM(1683);
+	HP_HUD_NPC_ID(1683);
 
 	private final int id;
 }

runelite-client/src/main/java/net/runelite/client/plugins/zalcano/ZalcanoPlugin.java

@@ -265,6 +265,7 @@ public class ZalcanoPlugin extends Plugin
 
 	private boolean isHealthbarActive()
 	{
-		return client.getVar(VarPlayer.ZALCANO_FORM) != -1;
+		int npcId = client.getVar(VarPlayer.HP_HUD_NPC_ID);
+		return npcId == ZALCANO_WEAKENED || npcId == ZALCANO;
 	}
 }