Fix /var/lib/prometheus 755 permission
Reported by @lahwaacz on IRC.
/var/lib/prometheus
is created as 755 (world readable) and Prometheus creates the files/directories with the default umask. Metrics aren't secrets, but I don't think they should be world readable.
This is more of a packaging issue, but we need to fix it manually anyways.
Edited by Kristian Klausen