CodeQL C# analyze: replace unauthorized dotnet NuGet feed

[Copilot]

Related Issue

Addresses the failing GitHub Actions check run Analyze (csharp) (92806375382), where CodeQL C# dependency discovery flagged an unreachable NuGet source.

Description

The C# CodeQL job was degraded by a 401 Unauthorized feed configured in source/dotnet/NuGet.config, causing dependency-restore failures/noise during build-mode none analysis. This change removes that inaccessible source from dotnet-specific NuGet configuration and aligns it with the repo’s accessible dependency feed.

• Root cause

  • source/dotnet/NuGet.config pointed to AdaptiveCards-public (pkgs.dev.azure.com/microsoft/...), which returned 401 in GitHub Actions.

• Change

  • Replaced the dotnet feed entry with AdaptiveCards-Dependencies (pkgs.dev.azure.com/shine-oss/...), consistent with repo usage.

• Expected effect

  • Eliminates the unauthorized feed from C# analysis dependency source enumeration, reducing restore failures and improving CodeQL C# analysis quality/signal.

<!-- source/dotnet/NuGet.config -->
<add key="AdaptiveCards-Dependencies" value="https://pkgs.dev.azure.com/shine-oss/AdaptiveCards/_packaging/AdaptiveCards-Dependencies/nuget/v3/index.json" />

Sample Card

Not applicable (CI/NuGet configuration change only).

How Verified

Validation should come from rerunning the Analyze (csharp) workflow, since this is a CI feed-configuration fix (no product/runtime behavior change).