Use correct section for log message if interface_driver import fails

If import of interface_driver in namespace_driver fails then message for
logger raises exception because of taking interface_driver from haproxy
section while actual interface_driver is in default section.

Closes-Bug: #1350320
Change-Id: Ic1e73c0cdccb2fff02f2adfbad677503c29ba88a
Merge "Use correct section for log message if interface_driver import fails"