bpo-45332: Fix broken Decimal test and benchmark

Modules/_decimal/tests/bench.py

@@ -7,10 +7,7 @@
 
 
 import time
-try:
-    from test.support import import_fresh_module
-except ImportError:
-    from test.test_support import import_fresh_module
+from test.support.import_helper import import_fresh_module
 
 C = import_fresh_module('decimal', fresh=['_decimal'])
 P = import_fresh_module('decimal', blocked=['_decimal'])

Modules/_decimal/tests/deccheck.py

@@ -47,7 +47,7 @@
 from queue import Queue, Empty
 from threading import Thread, Event, Lock
 
-from test.support import import_fresh_module
+from test.support.import_helper import import_fresh_module
 from randdec import randfloat, all_unary, all_binary, all_ternary
 from randdec import unary_optarg, binary_optarg, ternary_optarg
 from formathelper import rand_format, rand_locale

Modules/_decimal/tests/formathelper.py

@@ -31,7 +31,7 @@
 
 import os, sys, locale, random
 import platform, subprocess
-from test.support import import_fresh_module
+from test.support.import_helper import import_fresh_module
 from distutils.spawn import find_executable
 
 C = import_fresh_module('decimal', fresh=['_decimal'])