Enable CA2211: Non-constant fields should not be visible (#14073)

https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca2211

.globalconfig

@@ -391,7 +391,7 @@ dotnet_diagnostic.CA2207.severity = warning
 dotnet_diagnostic.CA2208.severity = suggestion
 
 # CA2211: Non-constant fields should not be visible
-dotnet_diagnostic.CA2211.severity = suggestion
+dotnet_diagnostic.CA2211.severity = warning
 
 # CA2213: Disposable fields should be disposed
 dotnet_diagnostic.CA2213.severity = none

src/System.Management.Automation/engine/remoting/fanin/PSSessionConfigurationData.cs

@@ -18,7 +18,9 @@ namespace System.Management.Automation.Remoting
     {
         /// <summary>
         /// </summary>
+#pragma warning disable CA2211 // Non-constant fields should not be visible
         public static bool IsServerManager;
+#pragma warning restore CA2211 // Non-constant fields should not be visible
 
         #region Public Properties