Fix scrolling issue on edit chat input

[QuentinMacheda]

Describe Your Changes

• Remove hidden overflow property to allow scrolling
• Update layout -> submit and cancel buttons are now below the textarea instead of being next to it.

Fixes Issues

• Closes #2855

Self Checklist

• [ ] Added relevant comments, esp in complex areas
• [ ] Updated docs (for bug fixes / features)
• [ ] Created issues for follow-up changes or refactoring needed