4.2.2 release checklist

[Tratcher]

• [x] Ensure the Version.props has the PreReleaseVersionLabel updated to the next preview - https://github.com/aspnet/AspNetKatana/pull/466
• [x] Identify and validate the build on the microsoft-reverse-proxy-official pipeline - https://dev.azure.com/dnceng/internal/_build/results?buildId=1763624&view=results
• [x] Release the build
• [x] Tag the commit
• [x] Draft release notes
• [x] Publish release notes
• [x] Close the old milestone
• [ ] Announce on social media
• [x] Request source code archival