Remove margin-left override on block-editor-inserter__toggle in wpcom-block-editor

[andrewserong]

This removes the left margin override on the block inserter in the header within the editor (The big plus button), which should return the alignment to match what's in core, and also resolve a mobile styling issue with this button.

Before

Mobile

Desktop

After

Mobile

Desktop

Changes proposed in this Pull Request

• Remove margin-left override on . block-editor-inserter__toggle in wpcom-block-editor as requested in [Gutenberg 7.7.1]: Fix editor header layout issues on mobile & tablet view. #40361 (comment)

Testing instructions

• Build and sync to your sandbox, or sandbox D42316-code (a pre-generated build)
• Sandbox your test site and widgets.wp.com
• Go to your test site in the block editor in Calypso, e.g. https://wordpress.com/block-editor/post/andysgutenbergedgetestsite.wordpress.com/243 and ensure the spacing looks like in the screenshots above (a little more margin for the plus button in the header)
• Go to the same page in wp-admin (e.g. https://andysgutenbergedgetestsite.wordpress.com/wp-admin/post.php?post=243&action=edit ) and ensure that the button margin remains the same
• As above but with a dotcom-fse site, ensure that the spacing looks okay, e.g.

Fixes #41386

[matticbot]

Test live: https://calypso.live/?branch=fix/wpcom-block-editor-margin-left-on-inserter-toggle

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[ramonjd]

Tested on D42316-code

LGTM

[alshakero]

Works as expected ✨