Remove unused usings the command line build decided to complain about

Author: davidwengier

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Completion/RazorCompletionItemResolver.cs

@@ -6,7 +6,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Threading;
-using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor.Tooltip;
 using Roslyn.Text.Adornments;
 

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Extensions/SyntaxListExtensions.cs

@@ -3,7 +3,6 @@
 
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
-using Microsoft.CodeAnalysis;
 
 namespace Microsoft.AspNetCore.Razor.Language.Syntax;
 

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Formatting/FormattingContext.cs

@@ -12,7 +12,6 @@
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Syntax;
 using Microsoft.AspNetCore.Razor.PooledObjects;
-using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Text;