TIMEBOXED: Flow YAML Editor: Source editor height increases with every character typed

Summary

The source editor in the Flow YAML editor appears to increase its height every time a single character is typed. This behavior seems unintended and creates a poor user experience.

Problem

When typing in the YAML editor, the editor container grows in height with each keystroke, rather than maintaining a consistent height or only adjusting when content exceeds the viewport.

Screen_Recording_2025-11-10_at_10.39.13

Screen_Recording_2025-11-10_at_10.40.27

Related

This issue was discovered while working on !211607 (merged)