https://steamuserimages-a.akamaihd.net/ugc/395549511456444697/5B9712994DB6503464794F180F050F28C666CF45/
(add a / at the end if the pic doesn't show)

It's located in the versalife building, between the canisters in what's called a magnetic chamber. It's not needed to get to the canisters or anywhere else in that area as far as I could tell?

For clarity's sake, is this vanilla, or modded?

Vanilla

Think it opens some of the containment fields within that chamber, though I think they can also be opened elsewhere, maybe a computer.

Even though the image is no longer available to check, I can confirm this is true; there is redundancy here, with a nearby terminal, in this case —— and almost always throughout the game.