Remove Confusing Button on Add User Modal in Administration

If you log onto a wiki using the admin account and then go to the administer wiki page, there is an option to add a new user in Users & Rights/Users. After you have created a new user, a button to log in as the new user appears, but after a second, it disappears without any action from the user. This button should be removed as it is confusing. See comments for more details.

Steps to Reproduce:
1. Log in as admin user
2. Go to the Administer Wiki
3. Click Users & Rights
4. Click Users
5. Click Add User and enter details
6. Click save
7. Confusing Button will appear