Update startMigrationPod value to false

Summary

Currently .Values.startMigrationPod is set to true which causes anchore-enterprise-migrate-db pod to start and run indefinitely.

This value should be set to false and only used as needed for manual migration steps.

Possible fixes

Update https://repo1.dso.mil/big-bang/product/packages/anchore-enterprise/-/blob/main/chart/values.yaml?ref_type=heads#L229 to false