bpo-35518: Skip test that relies on a deceased network service. (GH-15349)

If this service had thoroughly vanished, we could just ignore the
test until someone gets around to either recreating such a service
or redesigning the test to somehow work locally.  The
`support.transient_internet` mechanism catches the failure to
resolve the domain name, and skips the test.

But in fact the domain snakebite.net does still exist, as do its
nameservers -- and they can be quite slow to reply.  As a result
this test can easily take 20-30s before it gets auto-skipped.

So, skip the test explicitly up front.
(cherry picked from commit 5b95a150)
Co-authored-by: Greg Price <gnprice@gmail.com>

Lib/test/test_timeout.py

@@ -106,6 +106,7 @@ class TimeoutTestCase(unittest.TestCase):
     def tearDown(self):
         self.sock.close()
 
+    @unittest.skipIf(True, 'need to replace these hosts; see bpo-35518')
     def testConnectTimeout(self):
         # Choose a private address that is unlikely to exist to prevent
         # failures due to the connect succeeding before the timeout.