refactor(graphsync): cleanup integration test

DRY up integration test so it's more clear what each test is doing

impl/graphsync.go

@@ -97,7 +97,7 @@ func (gs *GraphSync) RegisterRequestReceivedHook(hook graphsync.OnRequestReceive
 
 // RegisterResponseReceivedHook adds a hook that runs when a response is received
 func (gs *GraphSync) RegisterResponseReceivedHook(hook graphsync.OnResponseReceivedHook) error {
-        gs.requestManager.RegisterHook(hook)
+	gs.requestManager.RegisterHook(hook)
 	return nil
 }