Draft: Add group-saml scenario to CNG pipeline

Tiffany Rearequested to merge
trea-add-SAML-to-cng into master

What does this MR do and why?

Add configuration for Test::Integration::GroupSAML scenario to test-on-cng/main.gitlab-ci.yml

References

Related to gitlab-org/quality/quality-engineering/team-tasks#4070

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