Delete Retired .openpublishing.build.ps1 script of default branch

[shujingMS]

This PR is auto-generated by Build Dev team to delete retired .openpublishing.build.ps1 script of default branch. Please help review and merge this PR if not auto-merged. For any concern or questions, contact shujingzhang@microsoft.com or Learn Content Publshing team.

[learn-build-service-prod[bot]]

Learn Build status updates of commit e21c528:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
.openpublishing.build.ps1	:white_check_mark:Succeeded	n/a (file deleted or renamed)

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
• Post your question in the Learn support channel

[prmerger-test[bot]]

PRMerger Results

Issue	Description
File Change Percent	This PR contains file(s) with more than 30% file change.
Unapproved file extension(s)	This PR contains file types that are not supported in the repo. The only supported file types are jpg, gif, png, json, svg and md.
Repository root file	This pull request contains a file submitted to the root of the repository.