ref(crons): Remove actually the last next_checkin (#49147)

Author: evanpurkhiser

tests/sentry/monitors/endpoints/test_monitor_ingest_checkin_details.py

@@ -44,7 +44,6 @@ def _create_monitor(self):
             slug="my-monitor",
             organization_id=self.organization.id,
             project_id=self.project.id,
-            next_checkin=timezone.now() - timedelta(minutes=1),
             type=MonitorType.CRON_JOB,
             config={"schedule": "* * * * *"},
             date_added=timezone.now() - timedelta(minutes=1),