[CDF-25682] avoid pandas dtype-mixing warning when filling NaNs (#1912)

# Description

Temporary suppressing pandas futurewarnings that are inconsequential but
confuse users
 
<img width="2254" height="994" alt="Screenshot 2025-09-03 at 14 57 01"
src="https://github.com/user-attachments/assets/5f01494d-be66-4b8b-a5f6-0af32d26920e"
/>



## Changelog

- [x] Patch
- [ ] Skip

## cdf

### Fixed

- Suppressing misleading pandas FutureWarning

## templates

No changes.

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Anders Albert <60234212+doctrino@users.noreply.github.com>
