fix: multischema schema level in message payload

[AceTheCreator]

This PR updates the handling of multi-format schemas by restructuring the schema property at the top level.

This changes ensure compatibility with the sample generator by flattening the schema structure while preserving its key properties.

fixes #1125

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

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