format one implementation file and remove SuppressMessage

[dsyme]

This formats one implementation file (fsiaux.fs). Builds on #13152

It also removes the old CodeAnalysis.SuppressMessage attributes throughout FSharp.Core. We haven't run FxCop-style automated code analysis on FSharp.Core for many years now, and have no plan to start running it again, so these attributes are both out of date and unchecked and best removed.

[dsyme]

Transient failure in MacOS:

The active test run was aborted. Reason: Test host process crashed : Stack overflow.
   at Microsoft.FSharp.Collections.MapTreeModule.mk[[System.Int64, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.__Canon, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]](Microsoft.FSharp.Collections.MapTree`2<Int64,System.__Canon>, Int64, System.__Canon, Microsoft.FSharp.Collections.MapTree`2<Int64,System.__Canon>)