i3/thinkpad: Add work3 display profile
i3/thinkpad: Remove redundant xrandr invocations

These extra invocations were used to work around nVidia's stupid
proprietary limitations that prevent more than two displays being active
at a time from a single card (even though none of these actually enabled
more than two displays simultaneously - their driver restricts switching
three or more displays at a time, like turn two on and a third off), and
are not needed now I'm using a sensible Intel GPU.