[3.13] Increase the timeout of test_large_content_length_truncated (GH-156398)

Increase the timeout of test_large_content_length_truncated

In Fedora, the test started to fail randomly when run on s390x architecture.
Increasing the timeout prevents the issue.
(cherry picked from commit 39921eb)

Co-authored-by: Karolina Surma <33810531+befeleme@users.noreply.github.com>

Author: miss-islington

Lib/test/test_httpservers.py

@@ -1023,7 +1023,7 @@ def test_large_content_length(self):
             self.assertEqual(res.read(), b'%d %d' % (size, size) + self.linesep)
 
     def test_large_content_length_truncated(self):
-        with support.swap_attr(self.request_handler, 'timeout', 0.001):
+        with support.swap_attr(self.request_handler, 'timeout', support.LOOPBACK_TIMEOUT):
             for w in range(18, 65):
                 size = 1 << w
                 headers = {'Content-Length' : str(size)}