Publishing pipeline failing with "error : DLL <name> for portable PDB not found

• This issue is blocking
  This error is causing publishing failures across many repositories

• This issue is causing unreasonable pain

Installer: https://dev.azure.com/dnceng/internal/_build/results?buildId=1417830&view=results
EFcore: https://dev.azure.com/dnceng/internal/_build/results?buildId=1417617&view=results
Runtime: https://dev.azure.com/dnceng/internal/_build/results?buildId=1417358&view=results
ASP.Net: https://dev.azure.com/dnceng/internal/_build/results?buildId=1417270&view=results

@epananth @hoyosjs Should we revert the changes to always publish as portable pdbs for now until we have some guidance on how to fix this, or we have a better strategy to determine if we should publish as portable?

This is causing another type of failure in aspnetcore's publishing:

https://dev.azure.com/dnceng/internal/_build/results?buildId=1417315&view=logs&j=ba23343f-f710-5af9-782d-5bd26b102304&t=6e277ba4-1c1e-552d-b96f-db0aeb4be20a

error : PDB0021: Document name doesn't match any pattern in Source Link: 'd:\a\_work\1\s\src\Azure\AzureAD\Authentication.AzureADB2C.UI\src\Areas\AzureADB2C\Pages\_ViewStart.cshtml

which looks to be the same issue as #7388. I'm going to roll back the portable PDB change. Looks like the approach of converting everything to portable won't work right now until we figure out all the issues.

This was unfortunately hidden for a while because of the bug where we stopped publishing symbols altogether.

Revert PR: #8034

I'm not seeing any more of these two error types in the promotion pipeline. #7988 still tracks getting the pdbs converted.