[3.11] gh-93453: Only emit deprecation warning in asyncio.get_event_loop when a new event loop is created (#99949)

It no longer emits a deprecation warning if the current event loop was set.

Co-authored-by: Łukasz Langa <lukasz@langa.pl>

Lib/test/test_asyncio/test_base_events.py

@@ -746,7 +746,7 @@ class BaseEventLoopTests(test_utils.TestCase):
     def test_env_var_debug(self):
         code = '\n'.join((
             'import asyncio',
-            'loop = asyncio.get_event_loop()',
+            'loop = asyncio.new_event_loop()',
             'print(loop.get_debug())'))
 
         # Test with -E to not fail if the unit test was run with