Merged manifests occasionally not getting uploaded

[mmitche]

There are a few cases where the merged manifest for a repo is not getting uploaded to blob storage. See:

e.g. assets/manifests/dotnet-cecil/0.11.5.0-alpha.25116.3/MergedManifest.xml

https://dev.azure.com/dnceng/internal/_build/results?buildId=2644424&view=results is the promotion build. Interestingly, there were some other assets that did get correctly uploaded:

Gathering drop for build 20250216.3 of https://github.com/dotnet/cecil
  Downloading asset assets/manifests/dotnet-cecil/0.11.5.0-alpha.25116.3/MergedManifest.xml
    Failed to download asset, errors shown below:
      Blob uri 'https://dev.azure.com/dnceng/internal/_apis/build/builds/2644416/artifacts for assets/manifests/dotnet-cecil/0.11.5.0-alpha.25116.3/MergedManifest.xml is of an unknown type
  Downloading asset [email protected]
    https://pkgs.dev.azure.com/dnceng/public/_apis/packaging/feeds/dotnet-tools/nuget/packages/Microsoft.SourceBuild.Intermediate.cecil/versions/0.11.5-alpha.25116.3/content =>
      D:\a\_work\1\a\drop\nonshipping\packages\Microsoft.SourceBuild.Intermediate.cecil.0.11.5-alpha.25116.3.nupkg
  Downloading asset [email protected]
    https://pkgs.dev.azure.com/dnceng/public/_apis/packaging/feeds/dotnet-tools/nuget/packages/Microsoft.DotNet.Cecil/versions/0.11.5-alpha.25116.3/content =>
      D:\a\_work\1\a\drop\nonshipping\packages\Microsoft.DotNet.Cecil.0.11.5-alpha.25116.3.nupkg
  Downloading asset assets/symbols/Microsoft.DotNet.Cecil.0.11.5-alpha.25116.3.symbols.nupkg
    https://dotnetbuilds.blob.core.windows.net/public/assets/symbols/Microsoft.DotNet.Cecil.0.11.5-alpha.25116.3.symbols.nupkg =>
      D:\a\_work\1\a\drop\nonshipping\assets\symbols/Microsoft.DotNet.Cecil.0.11.5-alpha.25116.3.symbols.nupkg

[mmitche]

This was precipitated by the accidental YAML change that stopped using the merged manifest for publishing. So the merged manifest is added to the BAR assets, but not published since this asset only exists in the merged manifest. This was fixed, so should be good now. We just need to flush these old deps through the system.