When rb-site upgrade fails to upgrade a database, it outputs a lot of

debug information to a log file in order to help diagnose the issue.

Part of this process logs connection information for the database as a

JSON string. This doesn't always work, as the data there is not

guaranteed to be JSON-compatible. This failure is sandboxed and does not

affect the rest of the log, but does mean we don't always get useful

information here.
This change switches this to log a pformat() of the connection

information, rather than a JSON log, in order to guarantee successful

logging.

Tested logging the information. Saw that the log was successful.