Fix analyzer errors on latest net9.0 SDK

[sebastienros]

Fixes ASP.NET continuous benchmarks running on latest SDK. New default analyzers are breaking the build.

[Piedone]

How about adding --warnaserror -p:RunAnalyzersDuringBuild=True to the CI builds so we don't get new warnings? I attempted this under #15719, thinking that we don't have any current warnings, but we have 900, actually. I see most of those fixed here (except for the one enforcing XML comments on public members; we can disable that).

[sebastienros]

How about adding --warnaserror -p:RunAnalyzersDuringBuild=True to the CI builds so we don't get new warnings?

That's a more involved decision. I am just reacting to the default analyzers added to SDK 9 to unblock the benchmarks which are run by multiple teams in MS.

[Piedone]

So doesn't this affect warnings already existing with .NET 8?

[sebastienros]

Reverted the changes VS made to editorconfig and it still works with net9.0 so they were not necessary