Remove call to unitName

[ghost]

• Calling unitName incorrectly appends -slice onto the end of the slice cgroup we are looking for
• Tested and can't see any obvious side effects by removing this call
• Fixes cgroups: cgroup deleted #47

[ghost]

Tested this and it works as expected. My test code worked as follows:

control, err := cgroups.Load(cgroups.SingleSubsystem(cgroups.Systemd, cgroups.Pids), cgroups.Slice("system.slice", "docker.service"))

[crosbymichael]

Can you sign your commit with the DCO? git commit -s --amend?

https://github.com/containerd/containerd/blob/master/CONTRIBUTING.md#sign-your-work

Thanks for working on this!

[codecov-io]

Codecov Report

Merging #52 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master      #52   +/-   ##
=======================================
  Coverage   13.32%   13.32%           
=======================================
  Files          23       23           
  Lines        4518     4518           
=======================================
  Hits          602      602           
  Misses       3800     3800           
  Partials      116      116

Impacted Files	Coverage Δ
systemd.go	0% <0%> (ø)	⬆️

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[ghost]

@crosbymichael Think I have done this - although I ended up with 3 commits for 1 tiny change :(

[crosbymichael]

@Sykomaniac if you amend and force push it should be one. you can git rebase -i HEAD~3 and squash

[ghost]

@crosbymichael Force push done - now only one commit

[crosbymichael]

LGTM

[estesp]

LGTM