As mentioned in #16644, move the update-translations.py script out of the bitcoin/bitcoin repo. This script is run infrequently by maintainers, and aside from #16644, doesn't see many changes. If it is going to be changed, it probably shouldn't consume review bandwidth in bitcoin/bitcoin anyways.
PR adding the script to the maintainer-tools repo: https://github.com/bitcoin-core/bitcoin-maintainer-tools/pull/31
Could also move some other scripts, such as gen-manpages.sh.