Removing SAML1 and backchannel support from our IdP

[Cantor, Scott]

> With all these changes in place, do I need to do anything else to
> disable/prevent use of the Artifact profile with Browser SSO?

No. Setting the property to false informs the IdP that requests for the artifact binding in an AuthnRequest can't be honored and eliminates the binding from the "outbound binding" collection that it iterates over when picking something to use.

-- Scott