fix: add Origin header in the proxy so to bypass django CSRF protections (#5591)

Fix the e2e tests that are failing due to the new CSRF protections introduced in Django 4.x. We simply add in the proxy the fake Origin header. 

Resolves [MAASENG-4353](https://warthogs.atlassian.net/browse/MAASENG-4353)

Author: r00ta

scripts/proxy.js

@@ -33,6 +33,7 @@ app.use(
     onProxyReq(proxyReq) {
       // Django's CSRF protection requires requests to come from the correct
       // protocol, so this makes XHR requests work when using TLS certs.
+      proxyReq.setHeader("Origin", `${process.env.MAAS_URL.replace(/\/$/, "")}`);
       proxyReq.setHeader("Referer", `${process.env.MAAS_URL}${proxyReq.path}`);
     },
     secure: false,