gh-125900: Clean-up logic around immortalization in free-threading (#125901)

* Remove `@suppress_immortalization` decorator
* Make suppression flag per-thread instead of per-interpreter
* Suppress immortalization in `eval()` to avoid refleaks in three tests
  (test_datetime.test_roundtrip, test_logging.test_config8_ok, and
   test_random.test_after_fork).
* frozenset() is constant, but not a singleton. When run multiple times,
  the test could fail due to constant interning.

1 files changed, 0 insertions, 3 deletions

diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py
index 5c6faa1626d..80e705a37c4 100644
--- a/Lib/test/test_capi/test_misc.py
+++ b/Lib/test/test_capi/test_misc.py
@@ -25,7 +25,6 @@ from test.support import import_helper
 from test.support import threading_helper
 from test.support import warnings_helper
 from test.support import requires_limited_api
-from test.support import suppress_immortalization
 from test.support import expected_failure_if_gil_disabled
 from test.support import Py_GIL_DISABLED
 from test.support.script_helper import assert_python_failure, assert_python_ok, run_python_until_end
@@ -481,7 +480,6 @@ class CAPITest(unittest.TestCase):
     def test_null_type_doc(self):
         self.assertEqual(_testcapi.NullTpDocType.__doc__, None)
 
-    @suppress_immortalization()
     def test_subclass_of_heap_gc_ctype_with_tpdealloc_decrefs_once(self):
         class HeapGcCTypeSubclass(_testcapi.HeapGcCType):
             def __init__(self):
@@ -499,7 +497,6 @@ class CAPITest(unittest.TestCase):
         del subclass_instance
         self.assertEqual(type_refcnt - 1, sys.getrefcount(HeapGcCTypeSubclass))
 
-    @suppress_immortalization()
     def test_subclass_of_heap_gc_ctype_with_del_modifying_dunder_class_only_decrefs_once(self):
         class A(_testcapi.HeapGcCType):
             def __init__(self):