Make SA0000 hidden but enabled by default

This change balances performance with usability of the workaround by
ensuring that all diagnostics are reported for files that are open in the
editor, without the performance overhead of enabling the workaround for
every file in the project.

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers/SpecialRules/SA0000Roslyn7446Workaround.cs

@@ -22,7 +22,7 @@ internal sealed class SA0000Roslyn7446Workaround : DiagnosticAnalyzer
         private static readonly string HelpLink = "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/blob/master/documentation/SA0000Roslyn7446Workaround.md";
 
         private static readonly DiagnosticDescriptor Descriptor =
-            new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, AnalyzerCategory.SpecialRules, DiagnosticSeverity.Info, AnalyzerConstants.DisabledByDefault, Description, HelpLink);
+            new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, AnalyzerCategory.SpecialRules, DiagnosticSeverity.Hidden, AnalyzerConstants.EnabledByDefault, Description, HelpLink);
 
         private static readonly Action<CompilationStartAnalysisContext> CompilationStartAction = HandleCompilationStart;