Shibboleth is only available on self-managed

What does this MR do and why?

Shibboleth is only available on self-managed, unless using SAML protocol which is documented in a separate page, per the note at the top of this doc.

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.