pytest_plugin: Increase poll timeout in consume_messages
This prevents flaky test_storage_replayer
in swh-storage
tests.
The test above often fails when running the swh-environment Jenkins job.
I managed to reproduce the issue locally by running that test again and again in an infinite loop.
Once the poll timeout increased running the test again in an infinte loop does not fail anymore.
Migrated from D6649 (view on Phabricator)