test_cli: Drop launchpad lister from the test_get_lister

Drop launchpad lister from the lister to check, its test setup is more involved than the
other listers. As its setup is not done in that test, it's actually connecting
anonymously to the launchpad server. So remove such lister from the test.

This should also fix the debian build which refuses such access [1]

[1] https://jenkins.softwareheritage.org/job/debian/job/packages/job/DLS/job/gbp-buildpackage/97/console

swh/lister/tests/test_cli.py

@@ -34,7 +34,10 @@ def test_get_lister(swh_scheduler_config):
 
     """
     db_url = init_db().url()
-    for lister_name in SUPPORTED_LISTERS:
+    # Drop launchpad lister from the lister to check, its test setup is more involved
+    # than the other listers and it's not currently done here
+    supported_listers = set(SUPPORTED_LISTERS) - {"launchpad"}
+    for lister_name in supported_listers:
         lst = get_lister(
             lister_name,
             db_url,