integration: Remove test_create_check_duplicate

[akerouanton]

moby/moby#46251 marks CheckDuplicate as deprecated. Any NetworkCreate request with a conflicting network name will now return an error.

[akerouanton]

@milas PTAL 🤗

[thaJeztah]

AttachContainerTest.test_attach_no_stream ___________________ tests/integration/api_container_test.py:1299: in test_attach_no_stream assert output == 'hello\n'.encode(encoding='ascii') E AssertionError: assert b'' == b'hello\n' E Use -v to get more diff ___________________ TestNetworks.test_create_check_duplicate ___________________ tests/integration/api_network_test.py:330: in test_create_check_duplicate self.tmp_networks.append(net_id['Id']) E TypeError: string indices must be integers 

Ha! Wondering if the last failure is an implicit type conversion; if the network ID could be parsed as a hexadecimal🤔

Let me try restarting CI

[thaJeztah]

Although it failed in 2 check, so perhaps that line needs to be removed (and was only needed for the second test?)

[thaJeztah]

LGTM

@milas PTAL