test: shouldn't use string to convert int64 to string

[HusterWan]

Signed-off-by: Michael Wan zirenwan@gmail.com

Ⅰ. Describe what this PR did

I made a mistake to use string to convert a int64 to string, in this PR, I would like to fix 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？)

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Merging #2690 into master will decrease coverage by 12.99%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master   #2690     +/-   ##
========================================
- Coverage   69.19%   56.2%    -13%     
========================================
  Files         278     273      -5     
  Lines       17392   17236    -156     
========================================
- Hits        12035    9688   -2347     
- Misses       4028    6193   +2165     
- Partials     1329    1355     +26

Flag	Coverage Δ
#criv1alpha2_test	?
#integration_test_0	36.23% <ø> (ø)	⬆️
#integration_test_1	35.17% <ø> (ø)	⬆️
#integration_test_2	36.28% <ø> (-0.03%)	⬇️
#integration_test_3	35.11% <ø> (-0.04%)	⬇️
#node_e2e_test	35.06% <ø> (+0.02%)	⬆️
#unittest	?

Impacted Files	Coverage Δ
client/container_restart.go	0% <0%> (-100%)	⬇️
client/image_pull.go	0% <0%> (-100%)	⬇️
apis/opts/sysctl.go	0% <0%> (-100%)	⬇️
client/volume_create.go	0% <0%> (-100%)	⬇️
client/image_remove.go	0% <0%> (-100%)	⬇️
client/daemon_update.go	0% <0%> (-100%)	⬇️
client/container_update.go	0% <0%> (-100%)	⬇️
client/image_load.go	0% <0%> (-100%)	⬇️
client/container_commit.go	0% <0%> (-100%)	⬇️
client/checkpoint_create.go	0% <0%> (-100%)	⬇️
... and 137 more

[rudyfly]

LGTM