[MAP] Removes Central Hallway Speedbumps

Removes the airlocks placed awkwardly in the middle of the central hallway loop. They've been replaced by more appropriate airlocks that separate each hallway segment instead.

https://dl.dropboxusercontent.com/u/831776/boxstation213_01%20-%20Copy.png

The airlocks were added in a while ago by Errorage as a speedbump to help people navigate as they would often sanic past the junction. This shouldn't be an issue anymore with HG's glorious speed nerf, where people can actually see where they're going now.