source-mixpanel-native: fix `cohort_members` OOMs #940

Job	Run time
py_connector (source-airtable, capture, v1, 1.0)	2m 8s
py_connector (source-asana, capture, v1, 1.0)	1m 27s
py_connector (source-facebook-marketing, capture, v4, 1.0)	2m 39s
py_connector (source-gladly, capture, v1, 1.0)	2m 9s
py_connector (source-google-ads, capture, v2, 1.0)	2m 3s
py_connector (source-google-sheets-native, capture, v1, 0.0)	2m 1s
py_connector (source-hubspot-native, capture, v1, 1.0)	2m 7s
py_connector (source-hubspot, capture, v5, 1.0)	1m 3s
py_connector (source-notion, capture, v2, 1.0)	2m 10s
py_connector (source-oracle-flashback, capture, v1, 1.0)	1m 21s
py_connector (source-linkedin-pages, capture, v1, 1.0)	1m 53s
py_connector (source-linkedin-ads-v2, capture, v1, 1.0)	2m 0s
py_connector (source-klaviyo, capture, v1, 1.0)	1m 55s
py_connector (source-recharge, capture, v1, 1.0)	2m 3s
py_connector (source-stripe-native, capture, v1, 1.0)	3m 3s
py_connector (source-zendesk-support, capture, v2, 1.0)	1m 39s
py_connector (source-iterable, capture, v2, 1.0)	2m 2s
py_connector (source-pendo, capture, v2, 1.0)	2m 3s
py_connector (source-twilio, capture, v2, 1.0)	2m 8s
py_connector (source-jira-native, capture, v2, 1.0)	1m 33s
py_connector (source-mixpanel-native, capture, v2, 1.0)	1m 51s
py_connector (source-brevo, capture, v1, 1.0)	2m 18s
py_connector (source-impact-native, capture, v2, 1.0)	2m 21s
py_connector (source-front, capture, v3, 1.0)	1m 52s
py_connector (source-genesys, capture, v1, 1.0)	1m 48s
	49m 37s

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