Ensure `ONLY_FULL_GROUP_BY` is not set by default
Ensure `ONLY_FULL_GROUP_BY` is not set by default

When our current version of Sequel is used against a MySQL 5.7.5+ an
error is encountered due to a change in default MySQL options that
includes ONLY_FULL_GROUP_BY.

```
Sequel::DatabaseError:
  Mysql2::Error: Expression #1 of ORDER BY clause is not in SELECT list,
  references column '<XYZ>' which is not in SELECT list; this is incompatible with DISTINCT
```

Reference: https://github.com/jeremyevans/sequel/issues/1514

This commit ensures that Sequel is operating on a connection it is
compatible with at all times given we are not planning an upgrade to
5.x.

ausaccessfed/saml-service,ausaccessfed/saml-service,ausaccessfed/saml-service,ausaccessfed/saml-service