Sites Dashboard: Remove layout-related overrides from Dotcom and A4A

[okmttdhr]

Related to https://github.com/Automattic/dotcom-forge/issues/10139

Proposed Changes

This PR removes layout-related overrides from Dotcom and A4A.

For details of individual overrides, please refer to this post's pfYzsZ-15D-p2 "Style Overrides Removal" and "Remaining Style Overrides" sections.

Why are these changes being made?

https://github.com/Automattic/dotcom-forge/issues/10139

Testing Instructions

On both Calypso and A4A Live;

• Go to /sites
• Click any site
• Ensure nothing breaks

A4A Live

• Go to /overview
• Go to /marketplace/assign-license
  • This page has a bit different layout from other A4A pages.
• Ensure nothing breaks

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-128643

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-128643&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-128643&env=a8c-for-agencies

[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.

[fushar]

Tested on wpcom and A4A; works well.

We might need to update other hosting pages like Themes, because now they have different border-bottom:

Sites	Themes

[andrii-lysenko]

Thank you for working on this.
This seems to work well and I haven't found any issues. The code looks good as well 👍

[okmttdhr]

We might need to update other hosting pages like Themes, because now they have different border-bottom:

I think we should update the border-block-end of .hosting-dashboard-layout__top-wrapper to align with the DataViews border color (i.e., the border color used in Dotcom Sites Dashboard rows).
The issue is that A4A currently uses different border colors for the rows from Core, the same as the .hosting-dashboard-layout__top-wrapper. Thus, we should also update A4A's border-color for rows.

The current border-color:

Dotcom	A4A

Created a follow-up issue: https://github.com/Automattic/dotcom-forge/issues/10178

[okmttdhr]

Confirmed it's working well even after #97804 ✔️