Align fast csproj parser with SDK update which removed global:: from generated global usings file

Author: jnm2

tools/ExampleTester.Tests/FastCsprojCompilationParserTests.cs

@@ -209,13 +209,13 @@ public static void ParsesImplicitUsings([Values("true", "enable", "false", "disa
             source.FilePath.ShouldBe("Test.GlobalUsings.g.cs");
             source.GetText().ToString().ShouldBe("""
                 // <auto-generated/>
-                global using global::System;
-                global using global::System.Collections.Generic;
-                global using global::System.IO;
-                global using global::System.Linq;
-                global using global::System.Net.Http;
-                global using global::System.Threading;
-                global using global::System.Threading.Tasks;
+                global using System;
+                global using System.Collections.Generic;
+                global using System.IO;
+                global using System.Linq;
+                global using System.Net.Http;
+                global using System.Threading;
+                global using System.Threading.Tasks;
                 
                 """);
         }

tools/ExampleTester/FastCsprojCompilationParser.cs

@@ -134,13 +134,13 @@ public static CsprojParseResult ParseCsproj(XDocument csprojDocument, string fil
         {
             generatedSources.Add(SyntaxFactory.ParseSyntaxTree("""
                 // <auto-generated/>
-                global using global::System;
-                global using global::System.Collections.Generic;
-                global using global::System.IO;
-                global using global::System.Linq;
-                global using global::System.Net.Http;
-                global using global::System.Threading;
-                global using global::System.Threading.Tasks;
+                global using System;
+                global using System.Collections.Generic;
+                global using System.IO;
+                global using System.Linq;
+                global using System.Net.Http;
+                global using System.Threading;
+                global using System.Threading.Tasks;
 
                 """,
                 parseOptions,