fix(ui5-illustrated-message): acc findings fixed

[PetyaMarkovaBogdanova]

3) IllustratedMessage (27 failing)

• Full spec failed.
• Failure pattern: repeated accessibility violations across static and interactive scenarios.
• Primary direction: missing or inconsistent ARIA/semantic associations in rendered structure.

IllustratedMessage	Broad repeated ARIA/semantic failures	full spec fails across static and interactive	Shared template primitive missing robust semantics/name relationships reused by many scenarios	Likely real, systemic	High	Start from base template: heading/body/image/action naming chains, role correctness, labelledby/describedby linkage	Static mode and interactive mode both expose valid names/roles; no repeated foundational violation

[ui5-webcomponents-bot]

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