gh-77476: Remove urllib HTTP test

[vstinner]

Remove test_sites_no_connection_close() which is skipped since 2018 (commit 36d56ea).

• Issue: ERROR: test_sites_no_connection_close (test.test_urllib2net.OtherNetworkTests) #77476

[vstinner]

Test skipped since 2018, since commit 36d56ea:

commit 36d56ea826caffbeac0fc0c6d90248b80516e33c
Author: INADA Naoki <methane@users.noreply.github.com>
Date:   Wed Apr 18 00:31:29 2018 +0900

    bpo-33295: Skip test using missing external site (GH-6504)
    
    `test_urllib2net.OtherNetworkTests.test_sites_no_connection_close`
    used `http://www.imdb.com/` but it is moved to https so the test is
    not valid anymore.  Skip test for the moment to allow CI to proceed.

See #77476.

[vstinner]

Merged, thanks for the review @orsenthil.