The Email Activation Flow cannot be completed because of invalid confirmation url

**Describe the bug**

I was experimenting with the `ENABLE_EMAIL_ACTIVATION` environment variable with self-hosted and I do receive an activation email to confirm my email address. Once I got the domain set properly in the `django_site` table the link pointed to the correct domain, however the front end route doesn't appear to be valid. The front end displayed the "Not Found" page. The link in the email was http://{{my-domain}}/activate/nw/{{unique-id-code}}. I looked through the frontend routes and didn't find one that matched this convention.

**To Reproduce**

Steps to reproduce the behavior:

1. Set up self-hosted with valid SMTP provider
2. Set `ENABLE_EMAIL_ACTIVATION` environment variable to `true`
3. Update `django_site` table to the appropriate domain
4. Register a new user with valid email address
5. Receive the Activation email used to confirm the email address of the new user
6. Click on the "Activate Flagsmith Account" link within the email
7. Flagsmith UI displays the "Not Found" page indicating an invalid route.

**Expected behavior**

Clicking the "Activate Flagsmith Account" performs the necessary actions to activate the newly registered account and either routes to the projects view or to the login view to complete the login process.

**Screenshots**
The email sent from Flagsmith to confirm the email address.

The "Not Found" page displayed after clicking the link inside of the email.

**How are you running Flagsmith?**

- [ ] Self Hosted with Docker
- [X] Self Hosted with Kubernetes
- [ ] SaaS at flagsmith.com
- [ ] Some other way