During a PR review of #41526, which would have ported #41400 into the release/5.0 branch, there was some PR feedback. Because that port PR was closed without merging, that feedback still needs to be addressed in master.

1. The message defined for the obsoletion needs to provide more context. See this comment.
2. The obsoletion needs to be added to the list of obsoletions document
3. We should add comments into the csproj files where the diagnostic is set to NoWarn. See this comment, but also apply that to the other csproj files too

This obsoletion is currently being absorbed in the aspnetcore repo, and improving these details might have helped smooth that experience out.