setup: use a variable for specific dependencies

Only do this on most recent labs.
setup: remove debug left-over code
setup: detect terminal size despite use of serial port

By using a CSI escape sequence, we can get terminal size. Unfortunately,
this doesn't work due to a bug in tmux. See:
 https://sourceforge.net/p/tmux/tmux-code/merge-requests/17/

This commit is just as a reference for future times.
setup: fix detection of terminal size despite tmux bug
setup: use terminal size detection for most recent labs