[automated] Remove temporary MTP exit-code normalization after .NET 11 SDK update #20565

Summary

PR #20308 adds aggregate dotnet test exit-code normalization as a temporary workaround for dotnet/sdk#56214. Aspire is pinned to .NET SDK 11.0.100-rc.1.26425.128, which predates the upstream fix.

The SDK fix merged in dotnet/sdk#56219 and was backported to the .NET 11 RC1 branch in dotnet/sdk#56296.

Removal trigger

Remove the workaround after Aspire upgrades to a .NET 11 SDK build verified to contain dotnet/sdk#56296 or the equivalent fix from dotnet/sdk#56219.

Scope

• Remove the aggregate exit-code normalization from the shared and Deployment E2E dotnet test paths.
• Remove normalization helpers and workflow plumbing that are no longer needed.
• Update docs/ci/mtp-args-pipeline.md to describe the fixed SDK behavior.
• Update or remove the focused normalization tests and test-trigger mappings with the implementation.

Validation

Before removing the workaround, verify that an all-skipped MTP run with --ignore-exit-code 8 returns success through dotnet test on the upgraded SDK, including the shared Bash and PowerShell test lanes and the Deployment E2E skip path.