E2E tests for access with enforced SAML SSO

What does this MR do?

Adds tests for checking user access to group, project, sub-group and sub-project when enforce SAML SSO is enabled.

Closes: gitlab-org/quality/testcases#241 (closed)

This is branched out of qa-shl-group-managed-accounts-e2e-tests

So, !19449 (merged) should merge before this.

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content