[3.15] gh-152402: Use support.nomemtest in test_pyexpat (GH-152403) (#152411)

gh-152402: Use `support.nomemtest` in `test_pyexpat` (GH-152403)
(cherry picked from commit 109c59e)

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

Author: miss-islington

Lib/test/test_pyexpat.py

@@ -1008,8 +1008,7 @@ class ExternalEntityParserCreateErrorTest(unittest.TestCase):
     def setUpClass(cls):
         cls.testcapi = import_helper.import_module('_testcapi')
 
-    @unittest.skipIf(support.Py_TRACE_REFS,
-                     'Py_TRACE_REFS conflicts with testcapi.set_nomemory')
+    @support.nomemtest
     def test_error_path_no_crash(self):
         # When an allocation inside ExternalEntityParserCreate fails,
         # the partially-initialized subparser is deallocated.  This