Fix the token count at the iteration node

[s2terminal]

Summary

fix #10655

I fixed the problem where the token count was not being added when using LLM in the iteration node.

Screenshots

Before:	After

"イテレーション" means "Iteration".

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[laipz8200]

Please make checks pass first.

[laipz8200]

Thank you for the contribution, could you please resolve the conflicts before we merge it?

[s2terminal]

Thank you for your help.