[CI] Clear unused dev tools before running CI

It seems we run out of disk space...

```yaml
      - name: free up disk space
        if: runner.os != 'Windows'
        run: |
          # Rust uses a lot of disk space, free up some space
          # https://github.com/actions/runner-images/issues/2840
          sudo rm -rf "$AGENT_TOOLSDIRECTORY"
```