backport: Stein
During the switch to Stein UCA, we did not switch all packages to python
3 for Debian/Ubuntu binary images. This change switches some more of
those packages.
Change-Id: I0bff21384d88ea678608392de2db1ba418c96665
Co-Authored-By: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>