Turn autocomplete off for the OTP field on login forms
    
    One-time passwords are one-time :-) so there is no point in remembering
    past values and offering them during subsequent logins.
    
    Similar to:
    https://github.com/fedora-infra/noggin/blob/82306f4fcbd1caef517d3379a3d3eb12ff06d6ff/noggin/templates/_login_form.html#L12
    
    Signed-off-by: Hunor Csomortáni <csomh@redhat.com>