Updated property for determining tar file

[mikefrobbins]

PR Summary

Fixes #3575, Fixes AB#432014 - Updated property for determining tar file

PR Checklist

• Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• Summary: This PR's summary describes the scope and intent of the change.
• Contributor's Guide: I have read the contributors guide.
• Style: This PR adheres to the style guide.

[learn-build-service-prod]

Learn Build status updates of commit b4f5578:

✅ Validation status: passed

File	Status	Preview URL	Details
docs-conceptual/azps-12.5.0/install-azps-offline.md	✅Succeeded	View (azps-12.5.0)
docs-conceptual/azps-13.4.0/install-azps-offline.md	✅Succeeded	View (azps-13.4.0)
docs-conceptual/azps-13.5.0/install-azps-offline.md	✅Succeeded	View (azps-13.5.0)

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