Add fallback message when preview changelog is empty (#46260)

Joseph T. Lyons created

Avoid publishing preview releasing that say nothing in the release
notes:

<img width="947" height="258" alt="SCR-20260107-ioxx"
src="https://github.com/user-attachments/assets/97204551-8f55-43fb-8c9c-35491a4f1378"
/>

Release Notes:

- N/A *or* Added/Fixed/Improved ...

Change summary

0 files changed

Detailed changes