chore: Update outdated GitHub Actions versions (#19577)

## Summary  
This PR updates outdated GitHub Action versions by migrating
`actions/download-artifact` from `v6` to `v7` in the following
workflows:
- `.github/workflows/prepare-release.yml`  
- `.github/workflows/release.yml`  
- `.github/workflows/release-insiders.yml`  

## Test plan  
The changes will be tested in the CI pipeline of the pull request.  

[×] Summary  
[×] Test plan