Fix Issue1012 test: use untyped lambda parameter (Sub(i) not Sub(i As Integer))

Parameters with explicit types in lambda expressions produce typed C#
parameters like (int i) =>. Using Sub(i) without an As-clause produces
the simpler i => form, which is what the test intended to demonstrate.

https://claude.ai/code/session_01AkwUvu3XuCdj3D4axoX4UX

Author: claude

Tests/CSharp/ExpressionTests/LambdaTests.cs

@@ -22,7 +22,7 @@ Private Sub BugRepro()
 
         Dim entities As New List(Of MyEntity)
 
-        Parallel.For(1, 3, Sub(i As Integer)
+        Parallel.For(1, 3, Sub(i)
                                Dim result As String = (From e In entities
                                                        Where e.EntityId = 123
                                                        Select e.Name).Single
@@ -44,7 +44,7 @@ private void BugRepro()
 
         var entities = new List<MyEntity>();
 
-        Parallel.For(1, 3, (i) =>
+        Parallel.For(1, 3, i =>
         {
             string result = (from e in entities
                              where e.EntityId == 123