mssql: skip rendering of mssql logos until we have a valid logo

public/app/plugins/datasource/mssql/plugin.json

@@ -10,8 +10,8 @@
       "url": "https://grafana.com"
     },
     "logos": {
-      "small": "img/mssql_logo.svg",
-      "large": "img/mssql_logo.svg"
+      "small": "",
+      "large": ""
     }
   },