fix CI: /var/lib/acme is not correctly cached on ns.testrun.org

[missytake]

CI fails currently, because it always tries to request new certs, but runs into the Let's Encrypt rate limit.

My guess is that /var/lib/acme is not correctly cached on ns.testrun.org. On both machines, they look like this right now:

/var/lib/acme
├── accounts
│   └── acme-v02.api.letsencrypt.org%2fdirectory
│       ├── 2aq44le2l75gv5t6iuv4zshhvv54nl57uh7aud5ug7nv2e7zsq5a
│       │   └── privkey
│       ├── 3a7y5cdcokldckxchcavh3ayi34gqi3l2etr47clmazuuxlebesq
│       │   └── privkey
│       ├── 433uh75o3b2rbzbp6v5f4n7kqljm22mqvfra424is7iltlz2jf4q
│       │   └── privkey
│       └── jo2alzaczy742a7dhzncbcv2wo2ldrihbfpshvabfe2j75d3pwtq
│           └── privkey
├── acme
│   ├── accounts
│   │   └── acme-v02.api.letsencrypt.org%2fdirectory
│   │       ├── 3a7y5cdcokldckxchcavh3ayi34gqi3l2etr47clmazuuxlebesq
│   │       │   └── privkey
│   │       └── 433uh75o3b2rbzbp6v5f4n7kqljm22mqvfra424is7iltlz2jf4q
│   │           └── privkey
│   ├── acme
│   │   ├── accounts
│   │   │   └── acme-v02.api.letsencrypt.org%2fdirectory
│   │   │       └── 433uh75o3b2rbzbp6v5f4n7kqljm22mqvfra424is7iltlz2jf4q
│   │   │           └── privkey
│   │   ├── certs
│   │   │   ├── lw2gx2tow3oh6bulj5dxxhsblj4pdvydcbrq2hiwanm2ygioof6q
│   │   │   │   ├── account -> ../../accounts/acme-v02.api.letsencrypt.org%2fdirectory/433uh75o3b2rbzbp6v5f4n7kqljm22mqvfra424is7iltlz2jf4q
│   │   │   │   ├── cert
│   │   │   │   ├── chain
│   │   │   │   ├── fullchain
│   │   │   │   ├── privkey -> ../../keys/exe5zlx5qdpukci6ent7lu53mxzrlcb3rhzqxf3jpb3sv2enzova/privkey
│   │   │   │   └── url
[...]

But only 3 levels deep, so maybe it's fine and it's actually something else...