Fix trailing comma in PublishData

[RikkiGibson]

Official build containing this change: https://dev.azure.com/dnceng/internal/_build/results?buildId=2505642&view=results

Recent official builds are failing since snap: https://dev.azure.com/dnceng/internal/_build/results?buildId=2505159&view=logs&j=7ae71e7c-d4fe-51ea-64cd-240849b77ab1&t=4f9c0653-2f18-500e-227d-19e80298b3dc

No PublishData found for branch 'main'. Using PublishData for branch 'main' with draft PR status.
The property 'insertionCreateDraftPR' cannot be found on this object. Verify that the property exists and can be set.
At D:\a\_work\_temp\548307e3-ff7c-45ff-9ccc-be3ab4e0bf53.ps1:12 char:3
+   $branchData.insertionCreateDraftPR = 'true'

The failure doesn't really make sense to me. Inspecting the diff from #10681, the most likely thing I can blame is the trailing comma is messing up parsing of the PublishData file.

Consider force merging for expediency @phil-allen-msft.