vcmi: remove old landmine property

config/spells/other.json

@@ -140,11 +140,6 @@
 							"appearAnimation" : "C09SPF0",
 							"appearSound" : "LANDMINE"
 						}
-					},
-					"damage":{
-						"type":"core:damage",
-						"optional":false,
-						"indirect":true
 					}
 				}
 			},