restore: cleanup cgroup properly in error path

[liusdu]

Cgroup yard is setup in crtools_prepare_shared. But it is not cleaned up
properly in some code path, which leads cgroup mountpoint leaking.

We can see this type of errors in runc's issue:opencontainers/runc#3042

[codecov-commenter]

Codecov Report

Merging #1541 (d5ae18e) into criu-dev (15266a4) will increase coverage by 0.05%.
The diff coverage is 66.23%.

❗ Current head d5ae18e differs from pull request most recent head f69ac4e. Consider uploading reports for the commit f69ac4e to get more accurate results

@@             Coverage Diff              @@
##           criu-dev    #1541      +/-   ##
============================================
+ Coverage     69.22%   69.28%   +0.05%     
============================================
  Files           135      136       +1     
  Lines         32784    32800      +16     
============================================
+ Hits          22696    22724      +28     
+ Misses        10088    10076      -12     

Impacted Files	Coverage Δ
criu/cgroup.c	77.73% <ø> (ø)
criu/mem.c	85.68% <ø> (+3.60%)	⬆️
criu/cr-restore.c	66.47% <50.00%> (-0.05%)	⬇️
criu/pidfd-store.c	66.18% <66.18%> (ø)
criu/cr-service.c	63.92% <75.00%> (+0.13%)	⬆️
criu/cr-dump.c	75.80% <100.00%> (+0.05%)	⬆️
criu/uffd.c	79.27% <0.00%> (-0.32%)	⬇️
criu/sk-unix.c	74.20% <0.00%> (-0.03%)	⬇️
compel/src/lib/infect.c	55.40% <0.00%> (+0.12%)	⬆️
... and 3 more

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