assistant2: Combine history views into one (#25293)

This PR combines the two history views in Assistant2 into one.

<img width="1309" alt="Screenshot 2025-02-20 at 5 34 37 PM"
src="https://github.com/user-attachments/assets/fbb08542-58b5-4930-8a20-254234e335fa"
/>

<img width="1309" alt="Screenshot 2025-02-20 at 5 34 41 PM"
src="https://github.com/user-attachments/assets/1174849e-edad-4e02-8bf3-bb92aafba4f8"
/>


Release Notes:

- N/A