docker: Add storage_driver variable choice

On runner0, docker doesn't recognize ZFS as storage driver:

root@runner0:~# docker info | awk 'NR>18 && NR < 26'
 Server Version: 24.0.6
 Storage Driver: overlay2
  Backing Filesystem: zfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
root@runner0:~# zfs list docker
NAME     USED  AVAIL     REFER  MOUNTPOINT
docker   366K  28.6G      109K  /var/lib/docker

When I checked on cassandra01 (with the same puppet configuration):

root@cassandra01:~# docker info | awk 'NR>14 && NR < 24'
 Server Version: 20.10.17
 Storage Driver: zfs
  Zpool: docker
  Zpool Health: ONLINE
  Parent Dataset: docker/lib
  Space Used By Parent: 2969600
  Space Available: 103373398016
  Parent Quota: no
  Compression: zstd
root@cassandra01:~# zfs list docker/lib
NAME         USED  AVAIL     REFER  MOUNTPOINT
docker/lib  2.83M  99.3G     2.83M  /var/lib/docker

This update don't modify the existing deployments, it just add an option on runner0:

ᐅ bin/octocatalog-diff -t gitlab_runner_storage_driver -f production runner0    
[...]
*******************************************
  File[/etc/default/docker-storage] =>
   parameters =>
     content =>
      @@ -15,3 +15,3 @@
       # DOCKER_STORAGE_OPTIONS = --storage-opt dm.metadatadev=/dev/mylogvol/my-docker-metadata --storage-opt dm.datadev=/dev/mylogvol/my-docker-data
      _
      -DOCKER_STORAGE_OPTIONS=""
      +DOCKER_STORAGE_OPTIONS=" --storage-driver zfs"
*******************************************
*** End octocatalog-diff on runner0.internal.staging.swh.network