fix(ras-acc): correctly update myaccount link after signing in

[chickenn00dle]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Closes https://app.asana.com/0/1207817176293825/1207836619707355/f

This PR ensures we are always updating the RAS-ACC my account button URL after successfully signing in or creating an account.

How to test the changes in this Pull Request:

1. As a new reader, create an account via the sign in button auth modal:
   
2. After signup is complete, select the my account button (pictured above) and confirm you are directed to my account.
3. Log out and go back to the home page
4. Log in to the same account via the sign in button
5. After logging in, select the my account button and confirm you are directed to my account.
6. Log out again and visit any page or post with a donate or checkout block as a reader
7. Go through the auth/checkout flow via the donate/checkout block
8. Once checkout is complete, select the my account button and confirm you are directed to my account.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[laurelfulford]

LGTM! 🎉