Config changes matching cnpool tests added in osmo-ttcn3-hacks, see 'Related'.
Keep a copy of the old config files named "-legacy", to not break the 'latest' tests, because osmo-hnbgw 'latest' does not yet support the new config options.
Add new containers based on debian-bookworm. Make some improvements over the bullseye containers while at it: * Remove sed for cversion.h, as the #error it is trying to replace is a warning now so it is a no-op, and we use our own eclipse-titan package instead of debian's package. * Make apt commands consistent * Move commands around to make better use of the cache * Clone osmo-python-tests from gerrit instead of gitea and invalidate cache when master changes * Tweak comments