Merge pull request #31039 from AdrianVovk/slice-freeze-thaw

Rework slice recursive freeze/thaw

diff --cc src/core/cgroup.c
Simple merge

diff --cc src/core/cgroup.h
Simple merge

diff --cc src/core/dbus-unit.c
Simple merge

diff --cc src/core/scope.c
Simple merge

diff --cc src/core/service.c
Simple merge

diff --cc src/core/unit.c
Simple merge

diff --cc src/core/unit.h
Simple merge