Replace AirflowException with ValueError in ProduceToTopicOperator

[FrankYang0529]

Based on CLAUDE.md, the community is actively reducing AirflowException usage. Replace raise AirflowException(...) with raise ValueError(...) in ProduceToTopicOperator.

• related: Move template-field validation/transformation out of operator __init__ (exemption-list burn-down) #70296

---

Was generative AI tooling used to co-author this PR?

• Yes - Claude Code

---

• Read the Pull Request Guidelines for more information. Note: commit author/co-author name and email in commits become permanently public when merged.
• For fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
• When adding dependency, check compliance with the ASF 3rd Party License Policy.
• For significant user-facing changes create newsfragment: {pr_number}.significant.rst, in airflow-core/newsfragments. You can add this file in a follow-up commit after the PR is created so you know the PR number.

[shahar1]

Apparently #70333 was opened earlier and addresses the problem more precisely.
One thing in mind - here you tried to address two issues in one PR (validate_operators_init_exemption.txt + known_airflow_execptions) - I prefer to handle each separtely.

Feel free to tackle the other operators (there are still plenty), or to turn this PR into addressing the known_airflow_exceptions part once the other is merged.

[FrankYang0529]

I will turn this one into addressing the known_airflow_exceptions part after #70333 is merged.

[shahar1]

We might need to take an intermediate step of creating an exception class that derives from both AirflowException and ValueError, because it will break the retry mechanism that is based on detecting the exception type.
It had been discussed in the past but was put on hold, I'll try to revive this discussion.