Prevent CI “Default” job failures from runner disk exhaustion

[Copilot]

The Default GitHub Actions job was failing during libconsensus.a archive creation with No space left on device. This change updates the workflow to reclaim runner disk space before dependency and project builds.

• Root cause addressed

  • The Ubuntu runner’s default preinstalled toolchains consumed enough disk to cause archive/link failure in the Build (Default) step.

• Workflow adjustment

  • Added a dedicated Free disk space step in .github/workflows/test.yml before dependency build.
  • Removes large unused preinstalled directories and prints current disk usage for quick observability in logs.

• Change scope

  • Workflow-only change; no production/runtime code paths modified.

- name: Free disk space
  run: |
    sudo rm -rf /usr/local/lib/android /usr/share/dotnet /opt/ghc
    df -h