Fix org_user_invite migration after backwards compat broken in oc_chef_a...

Update to handle breaking change introduced during refactor of oc_chef_authz for CS12.

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This is correct, in that it matches the expected input in oc_chef_user_org_invite.erl:158. I think the name chosen there is wrong; we aren't actually providing the user's authz_id, but the user's guid, which makes the whole thing confusing.