Check for test3's existence at start of freeipa_password_change
    
    This test expects to pick up from freeipa_webui, but that test
    is not fatal (i.e. it can fail and we still carry on to this
    one). We should probably make them independent, but for now,
    just check if 'test3' (one of the users freeipa_webui creates
    and that this test requires) actually exists, at the start. If
    not, we can just die right away.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>