ci: migrate to reusable workflows

[CodeVishal-17]

Description

Migrates the repository to use OpenClimateFix reusable GitHub Actions workflows.
Legacy branch and PR workflows have been disabled to avoid duplicate CI runs, while preserving scheduled jobs.
This aligns the repo with the new organisation-wide CI setup and ensures HF_TOKEN is passed correctly where required.

Related to openclimatefix/.github#86

How Has This Been Tested?

This change updates CI configuration only.
Testing is handled by GitHub Actions: the updated reusable workflows will run automatically on this PR and verify the setup.

• Yes

If your changes affect data processing, have you plotted any changes? i.e. have you done a quick sanity check?

• Yes

Checklist:

• My code follows OCF's coding style guidelines
• I have performed a self-review of my own code
• I have checked my code and corrected any misspellings

[CodeVishal-17]

Quick clarification on the scope of this PR:

This PR is primarily focused on migrating open-source-quartz-solar-forecast to the new OpenClimateFix reusable GitHub Actions workflows, in line with the org-wide CI changes.

During CI runs, we uncovered an existing issue where Sentry’s HuggingFaceHub integration fails during pytest collection (InferenceClient.chat_completion), which appears to be related to a dependency compatibility mismatch rather than the workflow migration itself.

I attempted a few minimal mitigations (skipping Sentry initialisation in CI/pytest) to unblock tests, but since this behaviour was not part of the original request and may need a more deliberate fix, I’m happy to revert those changes and keep this PR strictly scoped to CI migration only.

Please let me know how you’d prefer to proceed:

keep this PR limited to reusable workflow migration, or

handle the Sentry/HuggingFace issue separately in a follow-up PR.

Happy to adjust accordingly.