Sema: simplify "duplicate test name" error message

* Avoid redundant words ("found")
   - All compile errors are found by the compiler
 * Avoid unnecessary prepositions ("with")
   - There is a grammatically correct alternate word order without the
     preposition.

src/Module.zig

@@ -5354,7 +5354,7 @@ fn scanDecl(iter: *ScanDeclIter, decl_sub_index: usize, flags: u4) Allocator.Err
         const msg = try ErrorMsg.create(
             gpa,
             src_loc,
-            "found test declaration with duplicate name: {s}",
+            "duplicate test name: {s}",
             .{decl_name},
         );
         errdefer msg.destroy(gpa);