Enhance apt-get update handling for Debian/Ubuntu/Devuan containers by adding regional mirror lists and a fallback routine. The script now detects container timezone to prefer regional mirrors, builds a randomized candidate list, probes each mirror (timeout on TCP:80), rewrites /etc/apt/* sources to use a working mirror, and retries apt-get update until success. Keeps the existing non-interactive dist-upgrade and cleans up apt lists as before. This improves reliability of updates inside LXC containers when default mirrors are unreachable or misbehaving.