ipatests: test_trust: Change expected home directories for posix users
    
    Information from the AD about the home directories is not leveraged at
    all, but is generated from the username and domain. Fix the assumptions
    in the tests.
    
    Also changes 'Subdomain Test User' to 'Subdomaintest User' to be more
    consistent.
    
    https://fedorahosted.org/freeipa/ticket/4184
    
    Reviewed-By: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>