bugfix/#17186 check memory is assigned to chefclient slice

[ljblancoredborder]

Added a test for chefclient slice, because cgroup is not assigning a slice but it needs to be created

[the-label-bot]

The Label Bot has predicted the following:

Category	Value	Confidence	Applied Label
Kind	bug	0.884	✔️
Size	M	0.904	✔️

[malvads]

chef-client should not be assigned to a cgroup

[malvads]

We need to check all the services with something like

def is_in_redborder_cgroup(service)
  slice = `systemctl show #{service} --property=Slice`.split('=')[1]
  slice.chomp! != 'system.slice'
end

for all excluded should return false and for memservices should return true