Database client config on the server is ignored for db commands

[yorkshire-pudding]

This was found whilst working on #463, notably that in Lando I wanted to disable column-statistics as it was producing a warning.

Steps to reproduce

1. Set a config option that you will be able to test if has applied or not in a recognised location for the database (e.g. ~/.my.cnf)
2. Run bee db-export
3. Check if the option has applied

Expected result
System level db client options are applied

Actual result
System level db client options are NOT applied

[yorkshire-pudding]

Fixed in #480