This commit attempts to fix the integration test
SubscriberListingRepositoryTest::testReturnsCorrectCountForSubscribersInDynamicSegment()
that was failing sometimes on CircleCI. My theory is that the test was
failing because we were using created_at to order the subscribers in the
query that is used to get subscribers in a given dynamic segment, but
there is a chance the the value of this field is the same for all the
three subscribers that are created in this test. As this could lead to a
situation where the order of the returned subscribers changes, causing
the test to fail. To work around that, I changed the test to order the
results by ID. This way we should always get the subscribers in the same
order.
[MAILPOET-3451]
