Force CgroupsV1 on Ubuntu

PR containers#115 removed a force-cgroups-v2 setup for Ubuntu, possibly
assuming that Ubuntu uses cgroups v1 by default? That doesn't
seem to be the case: the Ubuntu I've looked at (via Cirrus
rerun-with-terminal) seems to default to v2. End result is
that we've been running CI for months without testing runc.
This PR forces cgroups v1 on Ubuntu, via grub boot args.

Also, remove a confusing "--exclude netavark et al". Again
in PR containers#115 the "TODO: remove this" comment was removed but
the actual code was not. I believe that was an oversight.

Both of these are completely untested. This PR is the test.

Signed-off-by: Ed Santiago <[email protected]>

cache_images/ubuntu_setup.sh

@@ -23,7 +23,8 @@ bash $SCRIPT_DIRPATH/ubuntu_packaging.sh
 
 if ! ((CONTAINER)); then
     warn "Making Ubuntu kernel to enable cgroup swap accounting"
-    SEDCMD='s/^GRUB_CMDLINE_LINUX="(.*)"/GRUB_CMDLINE_LINUX="\1 cgroup_enable=memory swapaccount=1"/'
+    warn "Forcing CgroupsV1"
+    SEDCMD='s/^GRUB_CMDLINE_LINUX="(.*)"/GRUB_CMDLINE_LINUX="\1 cgroup_enable=memory swapaccount=1 systemd.unified_cgroup_hierarchy=0"/'
     ooe.sh $SUDO sed -re "$SEDCMD" -i /etc/default/grub.d/*
     ooe.sh $SUDO sed -re "$SEDCMD" -i /etc/default/grub
     ooe.sh $SUDO update-grub