[3.12] gh-112186: Improve test case test_loop_is_closed_resource_warnings (GH-112187) (#112255)

(cherry picked from commit 18c6929)

Co-authored-by: DPR <[email protected]>

Author: miss-islington

Lib/test/test_asyncio/test_streams.py

@@ -1122,13 +1122,10 @@ async def inner(httpd):
         self.loop.set_exception_handler(lambda loop, ctx: messages.append(ctx))
 
         with test_utils.run_test_server() as httpd:
-            try:
+            with self.assertRaises(RuntimeError):
+                # This exception is caused by `self.loop.stop()` as expected.
                 self.loop.run_until_complete(inner(httpd))
-            # This exception is caused by `self.loop.stop()` as expected.
-            except RuntimeError:
-                pass
-            finally:
-                gc.collect()
+            gc.collect()
 
         self.assertEqual(messages, [])