Implement compression correctness validation in test_clp_json_compression

[coderabbitai]

Context

As part of the modular integration test design introduced in PR #1843, placeholder test functions were added for clp-json package tests. The test_clp_json_compression test currently validates package startup but needs implementation to actually compress a dataset and verify compression correctness.

Requirements

• Compress a sample dataset using the clp-json package
• Validate that the compression completed successfully
• Verify the correctness of the compressed output

References

• PR: feat(integration-tests): Modularize package tests with per-mode directories and module-scoped fixtures. #1843
• Discussion: feat(integration-tests): Modularize package tests with per-mode directories and module-scoped fixtures. #1843 (comment)
• File: integration-tests/tests/package_tests/clp_json/test_clp_json.py
• Requested by: @junhaoliao