python: re-enable pylint duplicate-code warnings

With the old library gone, there's nothing duplicated in the tree, so
the warning suppression can be removed.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Beraldo Leal <bleal@redhat.com>
Message-id: 20220330172812.3427355-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/setup.cfg

@@ -118,7 +118,6 @@ disable=consider-using-f-string,
         too-many-function-args,  # mypy handles this with less false positives.
         too-many-instance-attributes,
         no-member,  # mypy also handles this better.
-        duplicate-code,  # To be removed by the end of this patch series.
 
 [pylint.basic]
 # Good variable names which should always be accepted, separated by a comma.