Description:

Nomad's sandboxing became more strict with v1.5.0. see: https://developer.hashicorp.com/nomad/docs/upgrade/upgrade-specific#artifact-download-sandboxing

Now, artifact downloads are done as the `nobody` user. This requires that the nomad `data_dir` be world-navigable. The permissions of `/var/lib/nomad` is enforced by `/usr/lib/tmpfiles.d/nomad.conf` as `700`.

Currently, existing jobs that download artifacts are broken.

Suggestion:

/usr/lib/tmpfiles.d/nomad.conf

```diff
1c1
< d /var/lib/nomad 0700
---
> d /var/lib/nomad 0755
```

Additional info:
* package version(s): v1.5.0
* config and/or log files etc.
* link to upstream bug report, if any: https://discuss.hashicorp.com/t/nomad1-5-0-rc1-failed-to-download-artifact-error-permission-denied/50811/5

Steps to reproduce:

* run any job containing an [artifact](https://developer.hashicorp.com/nomad/docs/job-specification/artifact) stanza.
* job will fail during artifact download
* logs show:

```
[INFO] client.alloc_runner.task_runner: Task event: alloc_id=69a34e1c-4bbb-5742-9dcc-026434999754 task=fabio type="Task Setup" msg="Building Task Directory" failed=false
[INFO] client.alloc_runner.task_runner: Task event: alloc_id=69a34e1c-4bbb-5742-9dcc-026434999754 task=fabio type="Downloading Artifacts" msg="Client is downloading artifacts" failed=false
[ERROR] client.artifact: sub-process: OUTPUT="failed to sandbox artifact-isolation process: landlock failed to lock: permission denied"
[INFO] client.alloc_runner.task_runner: Task event: alloc_id=69a34e1c-4bbb-5742-9dcc-026434999754 task=fabio type="Failed Artifact Download" msg="failed to download artifact \"https://releases.hashicorp.com/consul/1.15.1/consul_1.15.1_linux_amd64.zip\": getter subprocess failed: exit status 1" failed=false
[ERROR] client.alloc_runner.task_runner: prestart failed: alloc_id=69a34e1c-4bbb-5742-9dcc-026434999754 task=fabio error="prestart hook \"artifacts\" failed: failed to download artifact \"https://releases.hashicorp.com/consul/1.15.1/consul_1.15.1_linux_amd64.zip\": getter subprocess failed: exit status 1"
```