[master] pmb.helpers: Handle workdir version suffix from 2.3.x

For the gitlab.com -> gitlab.postmarketos.org migration we needed to also migrate the workdir in pmb v2 since pmb v3 is not ready yet.

Therefore we need to handle that "7-2.x" workdir version and migrate correctly when switching to pmbootstrap v3.

See !2445 (merged)

.ci/integration.sh

+#!/bin/sh -e
+
+set -x
+
+if [ "$(id -u)" = 0 ]; then
+	exec su "${TESTUSER:-build}" -c "sh -e $0"
+fi
+
+pmbootstrap() {
+	./pmbootstrap.py --details-to-stdout "$@"
+}
+
+# Make sure that the work folder format is up to date, and that there are no
+# mounts from aborted test cases (pmbootstrap#1595)
+echo "Initializing pmbootstrap"
+yes '' | ./pmbootstrap.py --details-to-stdout init
+
+pmbootstrap work_migrate
+pmbootstrap -q shutdown
+
+# TODO: make device configurable?
+device="qemu-amd64"
+# TODO: make UI configurable?
+ui="phosh"
+pmbootstrap config device "$device"
+pmbootstrap config ui "$ui"
+
+# NOTE: --no-image is used because building images makes pmb try to
+# "modprobe loop". This fails in CI.
+echo "Building $ui image for $device"
+pmbootstrap -y install --zap --password 147147 --no-image
+
+echo "Building $ui image for $device, with FDE"
+pmbootstrap -y install --zap --password 147147 --fde --no-image