tests/vm: allow interactive login as root

This is useful when debugging and you want to add packages to an
image.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250108121054.1126164-30-alex.bennee@linaro.org>
2 files changed