Remove or alter `auditSources` section in VMR build

[NikolaMilosavljevic]

Nuget.client introduced source auditing with dotnet/sdk#42658, see NuGet/NuGet.Client#5939

This breaks source build, offline legs, as we do not use any online sources in those scenarios, and do not have internet access, see: #4548

There are 2 options:

• always remove this section
• remove only sources that aren't present in the list of package sources

Second option doesn't add a lot of value, as it will make the section content essentially empty. Also, all our offline sources are local and would not work with auditing anyway.