Message List - Design QA - Vertically center message body in the new Message Item UI

[rafaeltonholo]

Description

When users set the preview lines to 0, the message body is not vertically centred within the message row in the new Message Item UI. This creates an unbalanced layout and does not match the intended design.

Expected

When users set the preview lines to 0, the message body should be vertically centred within the available row height.

Actual

The message body appears at the top of the component.

Steps to reproduce

1. Turn on the feature flag use_compose_for_message_list_items
2. Navigate to Settings > General Settings > Display.
3. Set Preview lines to 0.
4. Navigate back to the Message List.
5. Observe the vertical alignment of the message body.