cgroup: Support 0-value for memory protection directives
    
    These make sense to be explicitly set at 0 (which has a different effect
    than the default, since it can affect processing of `DefaultMemoryXXX`).
    
    Without this, it's not easily possible to relinquish memory protection
    for a subtree, which is not great.
    
    (cherry picked from commit 22bf131be278b95a4a204514d37a4344cf6365c6)
    
    Related: #1763435
    
    patch_name: 0411-cgroup-Support-0-value-for-memory-protection-directi.patch
    present_in_specfile: true
    location_in_specfile: 411
    squash_commits: true