The alignment of the block quote isn't inside the content width in the editor

[JustinyAhin]

Describe the bug
This is a behavior that was already present in the Seedlet theme, but is even more annoying in Twenty Twenty One because of the separator at the bottom of the title. The quotation blocks are very offset with the width of the content.

To Reproduce
Steps to reproduce the behavior:

1. Within the editor, add one or many quotes blocks.
2. You'll notice that they're offset with the content width.

Expected behavior
The quote blocks should be well aligned with the content width.

Screenshots

Editor version (please complete the following information):

• WordPress version: trunk
• The website use the Gutenberg plugin, version 9.1.1

Additional context
Initially reported here #453 (review).