Configure MySQL logging to go to a file

[spgreenberg]

In order to support downloading of MySQL logs for customers, we need MySQL to log to a file.

Acceptance Criteria

• GIVEN MySQL instances that are logging
  WHEN logs are generated
  THEN they are written to a file
  AND downloadable via the AWS CLI

---

Security considerations

Logs are currently stored within AWS. This will not change as logs will remain in AWS, just in logs instead of a table. Postgres already logs to files now.

Implementation sketch

Setting changes: https://aws.amazon.com/premiumsupport/knowledge-center/rds-download-instance-logs/

• Update existing standalone MySQL RDS instances to log to a file
• Update the broker to ensure logging to a file is the default setting for standalone instances

[markdboyd]

Superseded by

#372
https://github.com/cloud-gov/private/issues/957