rename tests since they are valid opcodes that exist

VMTests/vmIOandFlowOperationsTest.json

 {
-    "dupAt51doesNotExistAnymore" : {
+    "dupAt51becameMload" : {
         "callcreates" : [
         ],
         "env" : {
@@ -1500,7 +1500,7 @@
             }
         }
     },
-    "swapAt52doesNotExistAnymore" : {
+    "swapAt52becameMstore" : {
         "callcreates" : [
         ],
         "env" : {
@@ -1542,4 +1542,4 @@
             }
         }
     }
-}
\ No newline at end of file
+}