(fix) Updates Testing Parameters based on Pull_Request_Target

[JPRuskin]

Description Of Changes

This commit updates the testing parameters to include image and cert-types based on the triggering action being a pull_request_target rather than just a pull_request.

Motivation and Context

I missed this when changing from pull_request to pull_request_target. This change brings the build into line.

Testing

Operating Systems Testing

N/A

Change Types Made

• [x] Bug fix (non-breaking change).
• ~[ ] Feature / Enhancement (non-breaking change).~
• ~[ ] Breaking change (fix or feature that could cause existing functionality to change).~
• ~[ ] Documentation changes.~
• ~[ ] PowerShell code changes.~

Change Checklist

• ~[ ] Requires a change to the documentation.~
• ~[ ] Documentation has been updated.~
• ~[ ] Tests to cover my changes, have been added.~
• ~[ ] All new and existing tests passed?~
• [ ] PowerShell code changes: PowerShell v3 compatibility checked?