Fix failing "Set Amulet Rules" integration test

[pawelperek-da]

Fixes failing tests due to deserialization error:

Request to http://localhost:5114/api/sv/v0/admin/sv/voterequest/create resulted in an unexpected exception: Daml-LF Party is empty
HTTP POST /api/sv/v0/admin/sv/voterequest/create from (127.0.0.1:44050): Responding with status code: 500 Internal Server Error

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[meiersi-da]

Thanks @pawelperek-da 🙇

[jose-velasco-ieu]

Thank you @pawelperek-da! LGTM