Treat failure in destroy of non-existing nested cgroups as a success.
Treat failure in destroy of non-existing nested cgroups as a success.

This may happen if certain daemon on the host creates and deletes
nested cgroups inside Mesos containers but the nested cgroups are not
managed by Mesos; we shouldn't fail the destroy. Ultimately the
rationale for this change is that if the goal is to destroy a cgroup
and the end result is that it's gone, then we should consider it a
success even though some nested cgroups are cleaned up out-of-band
by other entities.

Review: https://reviews.apache.org/r/53031/

gsantovena/mesos,neilconway/mesos,Gilbert88/mesos,zmalik/mesos,abudnik/mesos,zmalik/mesos,Gilbert88/mesos,chhsia0/mesos,asamerh4/mesos,andschwa/mesos,reneploetz/mesos,abudnik/mesos,dforsyth/mesos,kaysoky/mesos,craimbert/mesos,neilconway/mesos,reneploetz/mesos,asamerh4/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,jpeach/mesos,andschwa/mesos,neilconway/mesos,zmalik/mesos,gsantovena/mesos,asamerh4/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,gsantovena/mesos,verizonlabs/mesos,dforsyth/mesos,reneploetz/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,zmalik/mesos,andschwa/mesos,dforsyth/mesos,dforsyth/mesos,Gilbert88/mesos,reneploetz/mesos,gsantovena/mesos,kaysoky/mesos,verizonlabs/mesos,andschwa/mesos,yuquanshan/customizedMesos,kaysoky/mesos,Gilbert88/mesos,asamerh4/mesos,chhsia0/mesos,zmalik/mesos,dforsyth/mesos,asamerh4/mesos,kaysoky/mesos,abudnik/mesos,neilconway/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,andschwa/mesos,Aman-Jain-14/customizedMesos,reneploetz/mesos,Gilbert88/mesos,jpeach/mesos,abudnik/mesos,chhsia0/mesos,gsantovena/mesos,yuquanshan/customizedMesos,reneploetz/mesos,craimbert/mesos,abudnik/mesos,Gilbert88/mesos,jpeach/mesos,jpeach/mesos,craimbert/mesos,craimbert/mesos,gsantovena/mesos,reneploetz/mesos,chhsia0/mesos,andschwa/mesos,abudnik/mesos,Gilbert88/mesos,kaysoky/mesos,gsantovena/mesos,craimbert/mesos,asamerh4/mesos,abudnik/mesos,verizonlabs/mesos,asamerh4/mesos,yuquanshan/customizedMesos,zmalik/mesos,chhsia0/mesos,jpeach/mesos,kaysoky/mesos,craimbert/mesos,chhsia0/mesos,verizonlabs/mesos,chhsia0/mesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,jpeach/mesos,craimbert/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,zmalik/mesos,kaysoky/mesos,jpeach/mesos,neilconway/mesos