EoD and Unheard should have +20% buy limits at traders

[DrakiaXYZ]

This came up in support, there was a feature of EoD and Unheard editions that was only ever mentioned in a random patch notes page that we haven't implemented.

Patch notes: https://www.escapefromtarkov.com/news/id/301
Way down at the bottom, it notes: "Increased personal trader item limits by 20% for Edge of Darkness and The Unheard edition owners who upgraded from Edge of Darkness;"

Expectation: EoD and Unheard accounts should have a +20% boost to their purchase limits from traders. The patch notes specifically state "Unheard who upgraded from EoD" but I don't think we need to make that distinction.

Tested on live, this is a Standard account:

And this is an EoD account:

[DrakiaXYZ]

Closing in favor of issue: #990