test: fix blkio test case

[HusterWan]

Signed-off-by: ziren.wzr ziren.wzr@alibaba-inc.com

Ⅰ. Describe what this PR did

fix blkio test case, maybe caused by not rebase to latest code

Ⅱ. Does this pull request fix one issue?

fixes #2505

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

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Merging #2506 into master will increase coverage by 36.54%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #2506       +/-   ##
===========================================
+ Coverage   32.66%   69.21%   +36.54%     
===========================================
  Files         273      278        +5     
  Lines       18231    18387      +156     
===========================================
+ Hits         5956    12726     +6770     
+ Misses      11318     4220     -7098     
- Partials      957     1441      +484

Flag	Coverage Δ
#criv1alpha1test	31.35% <ø> (?)
#criv1alpha2test	35.44% <ø> (?)
#integrationtest	40.49% <ø> (?)
#nodee2etest	32.72% <ø> (+0.06%)	⬆️
#unittest	26.76% <ø> (?)

Impacted Files	Coverage Δ
daemon/mgr/snapshot.go	89.85% <0%> (-4.35%)	⬇️
daemon/mgr/container_stats.go	10.81% <0%> (-1.81%)	⬇️
daemon/mgr/spec_apparmor_linux.go	20% <0%> (ø)
daemon/mgr/spec_seccomp_linux.go	71.42% <0%> (ø)
credential/credential.go	0% <0%> (ø)
credential/file_store.go	0% <0%> (ø)
credential/helpers.go	44.44% <0%> (ø)
daemon/daemon.go	69.94% <0%> (+2.73%)	⬆️
cri/v1alpha2/cri.go	69.65% <0%> (+3.28%)	⬆️
pkg/utils/metrics/metrics.go	100% <0%> (+3.92%)	⬆️
... and 210 more

[fuweid]

LGTM