[CB-2] Fix bug in finding cluster in run

[rmoneys]

https://synccomputing.atlassian.net/browse/CB-2
Looks good with manual testing:

>>> from sync import awsdatabricks
>>> import logging
>>> logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s [%(name)s] %(message)s")
>>> r = awsdatabricks.create_submission_for_run(475643548716943, "Standard", "Jobs Compute", "f88a5e38-f953-48cf-b0f0-44546b10aff3")
2023-11-17 12:02:48,293 INFO [root] Waiting for cluster 1117-142827-rmf0tm5u to terminate
>>> r
Response(result='517f82c6-08a7-4390-8827-b5110d0901cd', error=None)