CKE4 is not supported by Olivero/Claro anymore

Problem/Motivation

Alongside CKE4 removal from core certain CSS files were also removed/edited resulting in (de facto) Olivero/Claro not supporting CKE4 anymore, which leads to a somewhat broken editor when using those themes in D10 + CKE4

Steps to reproduce

See https://git.drupalcode.org/project/drupal/-/commit/09f8f13d8a72b8e482cc6...

Proposed resolution

CKE4 should provide support at least for core themes, so it continue working as before

Remaining tasks

Implement it

User interface changes

Parity between CKE4 editor UI in D9 and D10 when using Olivero or Claro (and Gin, I think)

API changes

None

Data model changes

None