Clear up old Actions logs (#31735)

Clear up old Actions logs (#31735)

Part of #24256.

Clear up old action logs to free up storage space.

Users will see a message indicating that the log has been cleared if
they view old tasks.

<img width="1361" alt="image"
src="https://github.com/user-attachments/assets/9f0f3a3a-bc5a-402f-90ca-49282d196c22">

Docs: https://gitea.com/gitea/docs/pulls/40

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Co-authored-by: silverwind <me@silverwind.io>