Agreeing with @swalkinshaw, the best place to disable xdebug in group_vars would be to edit the existing xdebug_remote_enable (in group_vars/development/php.yml):
Slightly better question that will help me in multiple situations: after tweaking things like this, what’s the best way to enable them? vagrant up --provision seems like it might be destructive/overkill, but I’m not sure.