AO3-7319 Spambanning user should redirect to user's admin dashboard

[ScottVenkataraman]

Pull Request Checklist

This is related to the bug in Jira: https://otwarchive.atlassian.net/browse/AO3-7319

• [X ] Have you read "How to write the perfect pull request"?
• [X ] Have you read the contributing guidelines?
• [X ] Have you added tests for any changed functionality?
• [X ] Have you added the Jira issue number
  as the first thing in your pull request title (e.g. AO3-1234 Fix thing)
• Do you have fewer than 5 pull requests already open? If not, please wait
  until they are reviewed and merged before creating new pull requests.

Issue

https://otwarchive.atlassian.net/browse/AO3-7319

Purpose

What does this PR do?
Redirects user's to their admin dashboard after user deletes all of a spammer's creations.

Testing Instructions

How can the Archive's QA team verify that this is working as you intended?
See Jira bug for steps to reproduce/test

References

Credit

Scott Venkataraman (he/him)
What name and pronouns should we use to credit you in the Archive of Our Own's Release Notes?

[Bilka2]

Hi, Scott Venkataraman!

Thank you so much for this pull request. Someone will be along to review it soon.

I've updated the Jira issue status to In Review so no one mistakenly opens a duplicate pull request. If you'd like the ability to comment on, assign, and transition issues in the future, you're welcome to create a Jira account! It makes things a bit easier for us on the organizational side if the Full Name on your Jira account either closely matches the name you'd like us to credit in the release notes or includes it in parentheses, e.g. "Nickname (CREDIT NAME)."

Once you've done that (or if you've already done it -- Jira has been unreliable about showing us new accounts in the admin panel lately), you can either reply here or send an email to otw-coders@transformativeworks.org with your account name and email address and we'll set up the permissions for you.

Thanks again for contributing! If you have any questions, you can contact us at the same email address listed above.

[Bilka2]

Thank you again for contributing!