Remove CORS hack now that the envoy proxy removes the need for it

packages/server/package.json

@@ -83,7 +83,6 @@
     "@budibase/client": "^0.8.9",
     "@budibase/string-templates": "^0.8.9",
     "@elastic/elasticsearch": "7.10.0",
-    "@koa/cors": "^3.1.0",
     "@koa/router": "8.0.0",
     "@sendgrid/mail": "7.1.1",
     "@sentry/node": "5.19.2",

packages/server/src/app.js

@@ -1,5 +1,4 @@
 const Koa = require("koa")
-const cors = require("@koa/cors")
 const destroyable = require("server-destroy")
 const electron = require("electron")
 const koaBody = require("koa-body")
@@ -13,7 +12,6 @@ const Sentry = require("@sentry/node")
 const fileSystem = require("./utilities/fileSystem")
 
 const app = new Koa()
-app.use(cors())
 
 // set up top level koa middleware
 app.use(