Fix: fix the step group status if there's a suspending sub step

[FogDong]

Description of your changes

Fixes #

I have:

• Read and followed KubeVela's contribution process.
• Related Docs updated properly. In a new feature or configuration option, an update to the documentation is necessary.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

Special notes for your reviewer

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.09 ⚠️

Comparison is base (9c36c21) 67.64% compared to head (e29dad2) 67.55%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #158      +/-   ##
==========================================
- Coverage   67.64%   67.55%   -0.09%     
==========================================
  Files          50       50              
  Lines        4553     4553              
==========================================
- Hits         3080     3076       -4     
- Misses       1077     1080       +3     
- Partials      396      397       +1     

Flag	Coverage Δ
e2etests	23.11% <0.00%> (ø)
unit-test	64.27% <0.00%> (-0.09%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/tasks/builtin/step_group.go	66.94% <0.00%> (ø)

... and 1 file with indirect coverage changes

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[github-actions]

Successfully created backport PR #159 for release-0.5.