[E2E] PROMOTE TO BLOCKING: login_via_instance_wide_saml_sso_spec.rb

What does this MR do?

Promotes the following e2e tests to the blocking bucket:

1. Govern Instance wide SAML SSO user logs in to gitlab with SAML SSO | Testcase | Spec metrics

This MR was created based on data from reliable e2e test report: #473634 (closed)

(This MR was automatically generated by gitlab_quality-test_tooling at 2024-07-22 02:06:11 UTC)