Remove dead variable ElunaInstanceAI::canSave

It was used during development of instance scripting to smooth over
differences between loading instances on CMaNGOS and Trinity. However,
another workaround was used and it was no longer needed.

ElunaInstanceAI.h

@@ -60,13 +60,8 @@ private:
     //   either through `Load` or `Save`.
     std::string lastSaveData;
 
-    // Used to prevent saving this AI while it's still loading,
-    //   effectively nuking the data that's supposed to be loaded.
-    // Set to `false` while loading, `true` otherwise.
-    bool canSave;
-
 public:
-    ElunaInstanceAI(Map* map) : InstanceData(map), canSave(true)
+    ElunaInstanceAI(Map* map) : InstanceData(map)
     {
     }