Update appsettings.json

Microsoft.Azure.TypeEdge.Test/appsettings.json

@@ -1,10 +1,10 @@
 {
   "IotHubConnectionString":
-    "HostName=iotedgedev-iothub-7389d7.azure-devices.net;SharedAccessKeyName=iothubowner;SharedAccessKey=X34mtUSGftp5V1ocBVPHFo2RXyC4/uVURDFfUDlZp/c=",
+    "CONNECTION_STRING",
   "DeviceId": "UnitTestDevice",
   "Logging": {
     "LogLevel": {
       "Default": "Warning"
     }
   }
-}
+}