There is no setting to explicitly enable mesh interfaces in the config
wizard, so we need to enable mesh interfaces by default when the outdoor
mode is disabled (unless site.conf dictates otherwise).

The simplest way to achieve this is to delete the 5GHz mesh interface
sections when outdoor mode is disabled: 200-wireless would delete and
recreate them a moment later anyways, but by deleting them earlier we
ensure that the disabled status is initialized from site.conf again.

(cherry picked from commit 17bc6228)