Reactivate wsgi test related to socket option under python 3

Previously these tests was ignored surely because the WSGI tests
with SSL were broken due to some design changes introduced by python 3.7 [1]
in the SSL module of the stdlib.

However, unlike the other WSGI/SSL tests these changes don't use
the `requests` module or high level modules which are broken by
the monkey patching of the stdlib.

I suppose previous developers simply turned off all of tests related to
WSGI/SSL without much more details than "SSL tests with python 3 and eventlet
is broken" but some of them don't need much more work than just reactivate
them to be ran successfully.

This test seems to work without change, and it run successfully locally.

Let reactivate this test.

Change-Id: Ie0257af10a9439de8ec124a698ca75778bdf90b5
Partial-Bug: #1482633

oslo_service/tests/test_wsgi.py

@@ -346,7 +346,6 @@ class TestWSGIServerWithSSL(WsgiTestCase):
     @testtools.skipIf(platform.mac_ver()[0] != '',
                       'SO_REUSEADDR behaves differently '
                       'on OSX, see bug 1436895')
-    @testtools.skip("bug/1482633: test hangs on Python 3")
     def test_socket_options_for_ssl_server(self):
         # test normal socket options has set properly
         self.config(tcp_keepidle=500)