gh-117344: Skip flaky tests in free-threaded build (#117355)

The tests are not reliable with the GIL disabled. In theory, they can
fail with the GIL enabled too, but the failures are much more likely
with the GIL disabled.

Lib/test/test_concurrent_futures/test_process_pool.py

@@ -116,6 +116,7 @@ class ProcessPoolExecutorTest(ExecutorTest):
         for _ in range(job_count):
             sem.release()
 
+    @unittest.skipIf(support.Py_GIL_DISABLED, "gh-117344: test is flaky without the GIL")
     def test_idle_process_reuse_one(self):
         executor = self.executor
         assert executor._max_workers >= 4

Lib/test/test_concurrent_futures/test_thread_pool.py

@@ -41,6 +41,7 @@ class ThreadPoolExecutorTest(ThreadPoolMixin, ExecutorTest, BaseTestCase):
             sem.release()
         executor.shutdown(wait=True)
 
+    @unittest.skipIf(support.Py_GIL_DISABLED, "gh-117344: test is flaky without the GIL")
     def test_idle_thread_reuse(self):
         executor = self.executor_type()
         executor.submit(mul, 21, 2).result()