host-metrics: bind-mount /run/udev for diskio udev lookups

inputs.diskio (via gopsutil) reads /run/udev/data/b<major>:<minor> to
get per-device tags. Without the mount it falls back to the legacy
/dev/.udev/db/block:<name> path which doesn't exist on systemd hosts,
producing one "stat /dev/.udev/db/block:..." warning per device per
collection cycle.

stack_orchestrator/data/compose/docker-compose-host-metrics.yml

@@ -26,3 +26,8 @@ services:
       # Without this mount telegraf logs an "error reading /dev/<name>" warning
       # per device per collection cycle.
       - /dev:/dev:ro
+      # /run/udev is where modern systemd stores the udev database that
+      # gopsutil consults for per-device tags. Without it telegraf falls
+      # back to the legacy /dev/.udev/db/... path which doesn't exist on
+      # systemd hosts, producing "stat /dev/.udev/db/block:..." warnings.
+      - /run/udev:/run/udev:ro