bpo-40275: Use new test.support helper submodules in tests (GH-21315)

diff --git a/Lib/test/test_shelve.py b/Lib/test/test_shelve.py
index 9ffe2cb..ac25eee 100644
--- a/Lib/test/test_shelve.py
+++ b/Lib/test/test_shelve.py
@@ -2,6 +2,7 @@
 import shelve
 import glob
 from test import support
+from test.support import os_helper
 from collections.abc import MutableMapping
 from test.test_dbm import dbm_iterator
 
@@ -45,7 +46,7 @@
 
     def tearDown(self):
         for f in glob.glob(self.fn+"*"):
-            support.unlink(f)
+            os_helper.unlink(f)
 
     def test_close(self):
         d1 = {}
@@ -186,7 +187,7 @@
         self._db = []
         if not self._in_mem:
             for f in glob.glob(self.fn+"*"):
-                support.unlink(f)
+                os_helper.unlink(f)
 
 class TestAsciiFileShelve(TestShelveBase):
     _args={'protocol':0}