Extend OptProf baseline artifact retention to 3 years

[Copilot]

The OptProf ProfilingInputs artifactsDrop had no explicit dropRetentionDays, causing baseline data to expire after the default retention window — preventing reproduction/retraining of older builds against their original baseline.

Changes Made

• Added dropRetentionDays: '1095' to the OptProf artifactsDrop output in azure-pipelines/.vsts-dotnet-build-jobs.yml, consistent with the pattern used for the VS setup drop

- output: artifactsDrop
  ...
  usePat: true
  dropRetentionDays: '1095'   # 3 years
  dropMetadataContainerName: 'DropMetadata-OptProf'

Testing

CI/pipeline-only change; no unit tests applicable.

Notes

1095 days = 3 years. The VS setup drop uses '30' (extended by insertion + VS release); the OptProf baseline needs a longer window since it's used for retraining across multiple VS releases.

[dotnet-policy-service]

Hello @copilot, I noticed that you’re changing an .swr file or any file under src/Package/MSBuild.VSSetup.. Please make sure to validate this change by an experimental VS insertion. This is accomplished by pushing to an exp/* branch, which requires write permissions to this repo.