Update logging messages and separate dev-tools from the metadata module.

[YooSunYoung]

From the comments at #216 (review)

• Remove logging configuration that potentially contains tokens or credentials
• Remove multi-lines and markers from the logging messages
• Use json/as_dict for dictionary-like object logging
• Use warning instead error for non-critical errors
• Separate developer's tools from the scicat_metadata module

[YooSunYoung]

All logs from this module are only for consoles, and not meant to be streamed to graylog.
Ideally any failure in this check should block the deployment.