test: Remove flaky no cyclic garbage test (#6817)

The test flakes on 3.14t, and our test suite is not responsible for testing garbage collection details.

Author: alexander-alderman-webb

tests/test_serializer.py

@@ -1,4 +1,3 @@
-import gc
 import re
 from array import array
 
@@ -184,29 +183,6 @@ def test_max_value_length(body_normalizer):
     assert len(result["key"]) == max_value_length
 
 
-def test_serialize_does_not_leave_cyclic_garbage():
-    # Applications running with the GC disabled rely on serialize() being
-    # freed by reference counting alone, so it must not create reference
-    # cycles.
-    gc_was_enabled = gc.isenabled()
-    old_debug_flags = gc.get_debug()
-    gc.collect()
-    gc.disable()
-    try:
-        serialize({"extra": {"foo": [{"bar": i} for i in range(20)]}})
-        serialize({"foo": "bar"}, is_vars=True)
-
-        gc.set_debug(gc.DEBUG_SAVEALL)
-        gc.collect()
-        assert gc.garbage == []
-    finally:
-        gc.set_debug(old_debug_flags)
-        gc.garbage.clear()
-        gc.collect()
-        if gc_was_enabled:
-            gc.enable()
-
-
 def test_serialize_local_vars():
     # This was added to make sure we don't try to iterate over instances of
     # custom classes with an __iter__ method due to potential side effects