Remove posixAccount from service_find search filter
    
    This will allow cifs principals to be found. They were suppressed
    because they include objectclass=posixAccount.
    
    This is a bit of a historical anomaly. This was included in the
    filter from the initial commit (though it was person, not
    posixAccount). I believe it was a mistake from the beginning but
    it wasn't noticed because it didn't cause any obvious issues.
    
    https://pagure.io/freeipa/issue/8013
    
    Reviewed-By: Alexander Bokovoy <abbra@users.noreply.github.com>