Cache tests not working as expected

[dhadka]

The cache tests don't work as expected. We should delete both test folders before restoring, otherwise we're not really testing the action.

    - name: Generate files outside working directory
      shell: bash
      run: packages/cache/__tests__/create-cache-files.sh ${{ runner.os }} ~/test-cache

    # We're using node -e to call the functions directly available in the @actions/cache package
    - name: Save cache using saveCache()
      run: |
        node -e "Promise.resolve(require('./packages/cache/lib/cache').saveCache(['test-cache','~/test-cache'],'test-${{ runner.os }}-${{ github.run_id }}'))"
    - name: Restore cache using restoreCache()
      run: |
        node -e "Promise.resolve(require('./packages/cache/lib/cache').restoreCache(['test-cache','~/test-cache'],'test-${{ runner.os }}-${{ github.run_id }}'))"
    - name: Verify cache 
      shell: bash
      run: |
        packages/cache/__tests__/verify-cache-files.sh ${{ runner.os }} test-cache
        packages/cache/__tests__/verify-cache-files.sh ${{ runner.os }} ~/test-cache