[GITIAN] Use docker for the build on CI

Summary:
This allows for building the base image without requiring elevated
privileges.
Setup instructions can be found in D6989.

Test Plan:

./contrib/teamcity/build-configurations.py gitian-win

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D6990