Update $env:TF_BUILD to $env:CI after Github Action Switch

[JustinGrote]

This Var doesn't exist in Github Actions, it should be $CI https://docs.github.com/en/actions/learn-github-actions/variables

https://github.com/PowerShell/vscode-powershell/blob/cbe8b7bd3f131e7414f973c38bd3d1294c3382e9/vscode-powershell.build.ps1#L29-L33

Also in PSES https://github.com/PowerShell/PowerShellEditorServices/blob/70ef45d1655a7e5d37441095e1e5ab37408fe543/PowerShellEditorServices.build.ps1#L107-L108

Probably not causing a failure now but could pull in an unwanted dependency update that breaks the build in difficult to troubleshoot ways.

@andyleejordan please confirm I'm not missing something here.

[andyleejordan]

Ah so the only thing "missing" is that the release pipeline, where not bringing in a new dependency matters most, is still ADO with this variable. It should instead be $env:TF_BUILD -or $env:CI.

[JustinGrote]

There are other vars in there like the build or PR determination that need to be updated to the GH equivalents as well. Also matching either variable makes sense in case you need to rollback.