Mahi: Fix question bubble layout

Make sure the question bubble is right-aligned by adding a spacer before
the text bubble in the hierarchy.

Also add a pixeltest for this view to avoid future regression.

Fixed: b:331945182

Change-Id: I949e74315897aaebf6bc15859b84d512e00f4e83
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5405359


Commit-Queue: Andre Le <leandre@chromium.org>
Reviewed-by: Kevin Radtke <kradtke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280439}