gitlab-02 running out of disk space

we're eating 10GB a day, 14GB left, from my calculation.

checklist:

• quickfix: grow disk by 30GB
• document big users @lavamind
• talk with big users, here's the top 5:
  • jnewsome/sponsir-61-sims: 56GB jnewsome/sponsor-61-sims#13 (closed) @lavamind
  • tor/core/debian/tor : 27.5GB, #40616 (closed) @anarcat
  • l10n: 13GB, may be fixed in ci-templates@64f6d588
  • community: 11.8GB tpo/web/lego!51 (merged)
  • dgoulet/tor: 9.2GB tpo/core/tor#40562 (closed)
  • arti: ~4GB tpo/core/arti#327 (closed)
• draft rfc for reduced period @anarcat probably not necessary?
• decide if we reduce retention period. let's keep it like this for now (2022-02-10, 55GB left, 6GB/day, expected to flatten)
• document how to figure out which project is a big user (e.g. around here: https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/ci#finding-largest-volumes-users) @lavamind
• relate to larger storage problems (#40518, #40478 (closed))