test(e2e): acl-creation leaves a security header profile; teardown re-enables Cerberus #1909

Two low-severity E2E hygiene findings from #1906:

1. tests/security-enforcement/acl-creation.spec.ts creates a security headers profile and never deletes it (the ACL it creates is now cleaned up).
2. The security-teardown setup sometimes prints "Cerberus framework: DISABLED" and then re-enables it. Not caused by refactor: migrate websocket library from gorilla to coder/websocket #1906; the intended end state of the teardown should be confirmed.

Severity: low

Found in: #1906