provider/maas: Nix default node selection warning
provider/maas: Nix default node selection warning

This is the most likely scenario so don't warn about it.

Part of the fix for https://bugs.launchpad.net/juju/+bug/1629194.

frankban/juju,gabriel-samfira/juju,mikemccracken/juju,anastasiamac/juju,bac/juju,mjs/juju,howbazaar/juju,anastasiamac/juju,macgreagoir/juju,waigani/juju,marcmolla/juju,howbazaar/juju,alesstimec/juju,AdamIsrael/juju,macgreagoir/juju,bac/juju,bac/juju,macgreagoir/juju,AdamIsrael/juju,gabriel-samfira/juju,ericsnowcurrently/juju,perrito666/juju,anastasiamac/juju,frankban/juju,mjs/juju,perrito666/juju,dimitern/juju,alesstimec/juju,alesstimec/juju,mikemccracken/juju,frankban/juju,marcmolla/juju,reedobrien/juju,perrito666/juju,AdamIsrael/juju,mikemccracken/juju,mjs/juju,mjs/juju,bac/juju,anastasiamac/juju,anastasiamac/juju,reedobrien/juju,gabriel-samfira/juju,ericsnowcurrently/juju,waigani/juju,reedobrien/juju,marcmolla/juju,dimitern/juju,macgreagoir/juju,frankban/juju,howbazaar/juju,ericsnowcurrently/juju,mjs/juju,howbazaar/juju,ericsnowcurrently/juju,perrito666/juju,howbazaar/juju,dimitern/juju,alesstimec/juju,mjs/juju,gabriel-samfira/juju,mikemccracken/juju,AdamIsrael/juju,waigani/juju,mjs/juju,bac/juju,mikemccracken/juju,reedobrien/juju,marcmolla/juju,alesstimec/juju,gabriel-samfira/juju,frankban/juju,dimitern/juju,reedobrien/juju,perrito666/juju,ericsnowcurrently/juju,dimitern/juju,waigani/juju,macgreagoir/juju,marcmolla/juju