[MAP] AI's Common Channel intercom mic starts off.

Edits Box and MetaStation maps so that all three AIs start with the
microphone on their Common Channel intercoms off.

This partially addresses #5860. I wanted to keep this PR a pure map
change, as dealing with maps is a pure nightmare for both me and any
other coders with a map PR.

Full solution for the arrivals announcement and law broadcasts will be
in another PR.
Merge remote-tracking branch 'remotes/upstream/master' into Common_comms_MicOff

Conflicts:
	_maps/map_files/MetaStation.v39K.dmm
	_maps/map_files/tgstation.2.1.3.dmm
Merge pull request #5904 from GunHog/Common_comms_MicOff

[MAP] AI's Common Channel intercom mic starts off.