Delete package source mapping from NuGet.config

[mmitche]

Removed package source mapping configuration..

This is incompatible with some darc tool installs where add-source is needed.

May instroduce later if darc-install.ps1 is changed.

To double check:

• The right tests are in and the right validation has happened. Guidance: https://github.com/dotnet/arcade/blob/main/Documentation/Validation.md

[akoeplinger]

This broke the build but we didn't see it here because of the Azure Pipelines outage:

src/Microsoft.DotNet.Helix/Client/CSharp/Microsoft.DotNet.Helix.Client.csproj(0,0): error NU1507: (NETCORE_ENGINEERING_TELEMETRY=Restore) Warning As Error: There are 11 package sources defined in your configuration. When using central package management, please map your package sources with package source mapping (https://aka.ms/nuget-package-source-mapping) or specify a single package source. The following sources are defined: dotnet-public, dotnet-tools, dotnet-eng, dotnet-libraries, dotnet-libraries-transport, dotnet9, dotnet9-transport, dotnet10, dotnet10-transport, dotnet11, dotnet11-transport

[ViktorHofer]

FYI @richlander as you introduced it via 6198c7a

[premun]

This is now breaking in repos that still have PSM set:
https://dnceng.visualstudio.com/internal/_build/results?buildId=2937909&view=logs&j=d17d50ef-afac-5d4b-95a6-3014ce5cf7a4&t=9165f701-ce9c-5ceb-d4e8-411621a1b7a9&l=41

[akoeplinger]

It's a new error that got added by dotnet/sdk#52863

[Youssef1313]

Hitting this in testfx as well:

'D:\a\_work\1\s\.dotnet\dotnet.exe' tool install microsoft.dotnet.darc --version 1.1.0-beta.26176.1 --add-source 'https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json' -v minimal --tool-path 'D:\a\_work\1\s\artifacts\tmp\Debug\darc\341ee5f1-081b-4271-9c7e-7f25ab9b385f'
The --add-source option cannot be combined with package source mapping. To use an additional source, update your NuGet configuration file's source mapping settings. Learn more: https://aka.ms/nuget-package-source-mapping
The term 'D:\a\_work\1\s\artifacts\tmp\Debug\darc\341ee5f1-081b-4271-9c7e-7f25ab9b385f\darc.exe' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
##[error](NETCORE_ENGINEERING_TELEMETRY=PromoteBuild) There was an error while trying to publish build '308334' to default channels.

We will try to see if we can delete PSM as a workaround.

[premun]

We will switch over to --source instead of --add-source which should fix this. In the meanwhile, you can revert the .NET SDK bump in your global.json