Loader: Include the SQLState when logging a SQLException

[istreeter]

Currently, when a load fails we log the main error message from the exception. I have seen messages in the logs like:

HikariPool-1 - Connection is not available, request timed out after 30000ms.

....which comes from this line in Hikari. This is an example of a java SqlException which contains other helpful information, like the SqlState which is a dictionary of terms describing the exact reason for the failure. The logs will be much more helpful if we also log this SqlState as part of our log message.