PLT-6368 Changed client to always use window.location.origin over SiteURL (#6193)

webapp/utils/url.jsx

@@ -18,10 +18,6 @@ export function getShortenedURL(url = '', getLength = 27) {
 }
 
 export function getSiteURL() {
-    if (global.mm_config.SiteURL) {
-        return global.mm_config.SiteURL;
-    }
-
     if (window.location.origin) {
         return window.location.origin;
     }