bugfix: skip empty container dirs

[HusterWan]

Signed-off-by: Michael Wan [email protected]

Ⅰ. Describe what this PR did

If a container metadata dir is empty, just skip recover it

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

Yes I Do

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #2098 into master will decrease coverage by <.01%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #2098      +/-   ##
==========================================
- Coverage   65.16%   65.16%   -0.01%     
==========================================
  Files         208      208              
  Lines       16405    16407       +2     
==========================================
  Hits        10691    10691              
- Misses       4385     4386       +1     
- Partials     1329     1330       +1

Flag	Coverage Δ
#criv1alpha1test	33.17% <33.33%> (-0.08%)	⬇️
#criv1alpha2test	33.74% <33.33%> (-0.15%)	⬇️
#integrationtest	39.89% <33.33%> (+0.05%)	⬆️
#unittest	23.84% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
daemon/mgr/container_storage.go	49.23% <ø> (ø)	⬆️
pkg/meta/local.go	63.91% <33.33%> (-0.3%)	⬇️
cri/v1alpha2/cri.go	64.51% <0%> (-0.17%)	⬇️

[fuweid]

LGTM

If the umount fails, the action to remove container dir will be failed. Before we fix the umount issue, we should ignore the error.