Removes module variable required in GraalVM 22.2

[pivotal-david-osullivan]

Summary

The env var USE_NATIVE_IMAGE_JAVA_PLATFORM_MODULE_SYSTEM is no longer needed & is showing a build warning, this PR removes setting it at build time.

Use Cases

Closes #273

Checklist

• [ ] I have viewed, signed, and submitted the Contributor License Agreement.
• [ ] I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• [ ] I have added an integration test, if necessary.
• [ ] I have reviewed the styleguide for guidance on my code quality.
• [ ] I'm happy with the commit history on this PR (I have rebased/squashed as needed).