[SAML][IDP] SAML sessionIndex value should be a crypted value of LL::NG session_id
SAML sessionIndex should carry the real session_id (but encrypted). This will next be used in SLO to destroy the correct LL::NG session.
SAML sessionIndex should carry the real session_id (but encrypted). This will next be used in SLO to destroy the correct LL::NG session.