Fix: updates the error check on custom tasks to fail on errors

[Chaitanyareddy0702]

fix: updates the error check on custom tasks to fail on errors for workflow run

Description of your changes

This PR fixes the workflow phase showing succeded even if the workflow fails.

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

Tested the changes locally

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Summary by cubic

Fixed custom tasks so that workflow runs now fail correctly when post-stop hooks return errors.