[release pipeline] Compile-time pipeline reference causing build issues

[NikolaMilosavljevic]

With https://dev.azure.com/dnceng/internal/_git/dotnet-release/pullrequest/50753?_a=overview release pipeline's validation leg is failing if a pipeline build version does not exist. Check the source-build-release-validation.yml - the following code is the root cause of the failure:

resources:
  pipelines:
  - pipeline: dotnet-staging-pre10.0
    source: Stage-DotNet-Validate-Publish
    version: ${{ variables.PIPELINE_VERSION }}
  - pipeline: dotnet-staging
    source: Stage-DotNet-Prepare-Artifacts
    version: ${{ variables.PIPELINE_VERSION }}

Previously we always referenced the same pipeline for all releases, but that won't work anymore due to different release pipelines:

resources:
  pipelines:
  - pipeline: dotnet-staging
    source: Stage-DotNet-Validate-Publish
    version: ${{ variables.PIPELINE_VERSION }}

[NikolaMilosavljevic]

Not a blocker for P7 or any official release - moved to RC1 as we should fix this sooner rather than later.

[MichaelSimons]

@ellahathaway, IIRC, you were going to add a comment why this wasn't necessary and close it. TIA.

[ellahathaway]

Nikola has added a workaround for the current problem. We don't plan to implement a long-term fix because the release team is actively migrating their infrastructure to align with what .NET 10 uses. Once this migration is complete, artifacts will be published out of the Stage-DotNet-Prepare-Artifacts pipeline rather than Stage-DotNet-Validate-Publish.

This pipeline change will eventually break our existing release validation pipeline and remove the need for the workaround. Since the timing of the migration is uncertain, we'll plan to revisit and resolve this issue once the migration happens and our release pipeline actually breaks.