[3.15] gh-149977: Fix extra output of -m test test_lazy_import (GH-149978) (#150016)

gh-149977: Fix extra output of `-m test test_lazy_import` (GH-149978)
(cherry picked from commit 6d5be4b)

Co-authored-by: sobolevn <mail@sobolevn.me>

Author: miss-islington

Lib/test/test_lazy_import/__init__.py

@@ -10,6 +10,7 @@
 import unittest
 import tempfile
 import os
+import contextlib
 
 from test import support
 from test.support.script_helper import assert_python_ok
@@ -441,10 +442,14 @@ def tearDown(self):
 
     def test_lazy_import_pkg(self):
         """lazy import of package submodule should load the package."""
-        import test.test_lazy_import.data.lazy_import_pkg
+        out = io.StringIO()
+
+        with contextlib.redirect_stdout(out):
+            import test.test_lazy_import.data.lazy_import_pkg
 
         self.assertIn("test.test_lazy_import.data.pkg", sys.modules)
         self.assertIn("test.test_lazy_import.data.pkg.bar", sys.modules)
+        self.assertIn("BAR_MODULE_LOADED", out.getvalue())
 
     def test_lazy_import_pkg_cross_import(self):
         """Cross-imports within package should preserve lazy imports."""