Join schedules to timeseries

[rajeee]

Fixes # .

Pull Request Description

We used to concatenate the schedules to timeseries before - it stopped working after ResStock changed the naming on the schedule files. This PR re-introduces it.

Checklist

Not all may apply

• Code changes (must work)
• Tests exercising your feature/bug fix (check coverage report on Checks -> BuildStockBatch Tests -> Artifacts)
• Coverage has increased or at least not decreased. Update minimum_coverage in .github/workflows/coverage.yml as necessary.
• All other unit and integration tests passing
• Update validation for project config yaml file changes
• Update existing documentation
• Run a small batch run on Kestrel/Eagle to make sure it all works if you made changes that will affect Kestrel/Eagle
• Add to the changelog_dev.rst file and propose migration text in the pull request