Fix make-base-vm distro according to current CI configuration

Summary: Did a dry-run of our gitian builds and realized the build instructions are out-of-date.

Test Plan: Ran this locally.

Reviewers: deadalnix, schancel, #bitcoin_abc

Reviewed By: schancel, #bitcoin_abc

Subscribers: teamcity

Differential Revision: https://reviews.bitcoinabc.org/D1988