Remove special case handling of CreateDiagnosticProviderAndFixer throwing an exception

src/EditorFeatures/TestUtilities/Diagnostics/AbstractDiagnosticProviderBasedUserDiagnosticTest.cs

@@ -41,16 +41,7 @@ public void TestSupportedDiagnosticsMessageTitle()
         {
             using (var workspace = new AdhocWorkspace())
             {
-                DiagnosticAnalyzer diagnosticAnalyzer;
-                try
-                {
-                    diagnosticAnalyzer = CreateDiagnosticProviderAndFixer(workspace).Item1;
-                }
-                catch (NotSupportedException)
-                {
-                    return;
-                }
-
+                var diagnosticAnalyzer = CreateDiagnosticProviderAndFixer(workspace).Item1;
                 if (diagnosticAnalyzer == null)
                 {
                     return;
@@ -74,16 +65,7 @@ public void TestSupportedDiagnosticsMessageDescription()
         {
             using (var workspace = new AdhocWorkspace())
             {
-                DiagnosticAnalyzer diagnosticAnalyzer;
-                try
-                {
-                    diagnosticAnalyzer = CreateDiagnosticProviderAndFixer(workspace).Item1;
-                }
-                catch (NotSupportedException)
-                {
-                    return;
-                }
-
+                var diagnosticAnalyzer = CreateDiagnosticProviderAndFixer(workspace).Item1;
                 if (diagnosticAnalyzer == null)
                 {
                     return;
@@ -110,16 +92,7 @@ public void TestSupportedDiagnosticsMessageHelpLinkUri()
         {
             using (var workspace = new AdhocWorkspace())
             {
-                DiagnosticAnalyzer diagnosticAnalyzer;
-                try
-                {
-                    diagnosticAnalyzer = CreateDiagnosticProviderAndFixer(workspace).Item1;
-                }
-                catch (NotSupportedException)
-                {
-                    return;
-                }
-
+                var diagnosticAnalyzer = CreateDiagnosticProviderAndFixer(workspace).Item1;
                 if (diagnosticAnalyzer == null)
                 {
                     return;

src/EditorFeatures/VisualBasicTest/Diagnostics/AddImport/AddImportTests_NuGet.vb

@@ -30,7 +30,9 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.CodeActions.AddImp
         End Function
 
         Friend Overrides Function CreateDiagnosticProviderAndFixer(workspace As Workspace) As (DiagnosticAnalyzer, CodeFixProvider)
-            Throw New NotSupportedException()
+            ' This is used by inherited tests to ensure the properties of diagnostic analyzers are correct. It's not
+            ' needed by the tests in this class, but can't throw an exception.
+            Return (Nothing, Nothing)
         End Function
 
         Friend Overrides Function CreateDiagnosticProviderAndFixer(workspace As Workspace, parameters As TestParameters) As (DiagnosticAnalyzer, CodeFixProvider)