fix: return display-version tests as generated_tests in testgen response (#2477)

## Summary
- The `/testgen` response's `generated_tests` field contained the
assert-removed version with `codeflash_output` assignments
- When the CLI's testgen review fell back to this field (instead of
`raw_generated_tests`), the review LLM flagged every test as a "no-op
assignment"
- Now returns the display version (asserts kept, no instrumentation) as
`generated_tests`, matching what the repair endpoint already does
- Also applies isort to the display source for consistency

django/aiservice/core/languages/python/testgen/generate.py

@@ -309,6 +309,13 @@ async def generate_regression_tests_from_function(
             generated_test_source = sorted_generated_tests
         except Exception:  # noqa: BLE001
             sentry_sdk.capture_message("isort caused a syntax error in testgen; returning un-sorted code.")
+
+        sorted_display_source = safe_isort(raw_display_source)
+        try:
+            parse_module_to_cst(sorted_display_source)
+            raw_display_source = sorted_display_source
+        except Exception:  # noqa: BLE001
+            pass
         tree = ast.parse(generated_test_source, feature_version=python_version[:2])
         if not has_test_functions(tree):  # sanity check, after all the processing somehow no test functions
             msg = f"No test functions were found in the generated test code. trace_id={trace_id}"
@@ -420,7 +427,7 @@ async def testgen_python(
             )
 
         return 200, TestGenResponseSchema(
-            generated_tests=generated_test_source,
+            generated_tests=raw_display_source,
             instrumented_behavior_tests=instrumented_behavior_tests,
             instrumented_perf_tests=instrumented_perf_tests,
             raw_generated_tests=raw_display_source,