Changed the format of the debian12 ironbank.list file to hopefully work with...

Description

https://repo1.dso.mil/platform-one/private/big-bang/ironbank/ironbank-bootstrap/-/issues/1765

Updates the file the Debian image uses to find repositories for apt. Here is an example pipeline in Mario: https://code-ib-mario.staging.dso.mil/dsop/jwuebbl/debian-12.x/-/pipelines/25126