[comp datarouter] Component Integration Test completion

## What

Complete the Component Integration Test (`wp__verification_comp_int_test`) for the component datarouter: add a formal `document::` with `:realizes: wp__verification_comp_int_test` to existing test files. Integration testing verifies the component architecture and requirements.

## How

**Process step:** [wf__verification_comp_int_test](https://eclipse-score.github.io/process_description/main/process_areas/verification/verification_workflows.html#wf__verification_comp_int_test)
Existing artifact: [[score/test/component/datarouter/](logging/score/test/component/datarouter/)]([score/test/component/datarouter/](logging/score/test/component/datarouter/))

## Definition of Done

All criteria of the [Verification Guideline](https://eclipse-score.github.io/process_description/main/process_areas/verification/guidance/verification_guideline.html) are met.

## Template & Folder Structure

- **Template:** [Module Template – Overview](https://eclipse-score.github.io/module_template/main/index.html)
- **Folder:** `score//tests/` – see [Module Folder Structure](https://eclipse-score.github.io/module_template/main/index.html#module-layout)

*Please apply the linked template and folder structure to ensure consistency across the S-CORE project.*