[Bug]: Metrics aren't collected with RunPod

[peterschmidt85]

Steps to reproduce

1. Run any run on RunPod
2. Check Metrics tab in UI (or use dstack metrics CLI)

Actual behaviour

1. No metrics available

Expected behaviour

1. Metrics are available

dstack version

0.20+

Server logs

Additional information

Since 616fa31 when we dropped cgroup v1, RunPod metrics stopped working.

Apparently for some reason, RunPod still mounts only v1 cgroups.