Fix test_login in test_user_browser.py

Fix test_login in test_user_browser.py

It tried to use the pbkdf2 hash as the password. Use the username instead, as that
is what create_user sets.

Then it compared the test user username to testuser, rather than the username, which
is dynamically generated. Compare to the generated username.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Stephen Finucane <stephenfinucane@hotmail.com>