Fix CI: force fresh list buffer alloc in test_no_memory (gh-126703)

Small-list freelist entries keep their ob_item buffers, so a plain [None]
after inject_memory_error() may succeed instead of failing. Repeat the list
to a size the freelists cannot satisfy, forcing a real allocation.

Co-authored-by: Muse Code (Meta Muse Spark)

Author: ambv

Lib/test/test_list.py

@@ -384,7 +384,9 @@ def test_no_memory(self):
              None, None, None, None, None, None, None, None, None,]
         del l
         support.inject_memory_error()
-        l = [None]
+        # Repeat to force a fresh ob_item allocation: entries on the small
+        # list freelists keep their buffers, so a plain [None] may succeed.
+        l = [None] * 30
         """)
         rc, _, _ = assert_python_failure("-c", code)
         if support.MS_WINDOWS: