Feature: Nuke the Mozilla Guest wireless profile via LaunchAgent after Mozilla Corp is created.

[luciusbono]

Since we build machines on Mozilla Guest, but ask users to join Mozilla Corp later on, having Mozilla Guest go away automatically seems like a good idea.

Two paths:

1. Just have dinobuildr nuke Mozilla Guest as the final step of the build (or at next boot with a launchagent)
2. Have dinobuildr drop a launchagent that waits around until it sees the Mozilla Corp profile, then nukes Mozilla guest

These are just rough ideas of how this might work, and there are likely technical hurdles we need to work out.