chore: minor improvments in data ingestion

[jychp]

This PR adds a new date-parsing utility and applies it across multiple intel ingestion modules, updates related tests, and removes some legacy cleanup jobs and indexes.

• Introduce dict_date_to_datetime in cartography/util.py and wire it into transforms for various intel connectors to normalize date fields and drop empty strings.
• Update test expectations in Semgrep integration tests to remove scan_time.
• Remove JSON-based cleanup jobs for DigitalOcean and Crowdstrike and drop associated indexes.