Opt in already validatable CKEditor 5 text editor settings + configurable CKEditor 5 plugin's settings to FullyValidatable

Note that without ✨ [PP-1] Mark parts of CKEditor 5 and Editor config schema as fully validatable Postponed this will not have any effect due to the way 📌 Configuration schema & required keys Fixed works (see the corresponding change record: https://www.drupal.org/node/3404425 → ).

None of the config schema types in ckeditor5.schema.yml are "absolute roots": none of them are of type: config_object or type: config_entity, and hence none of these are enforced just yet. Only after #3412361 lands will this cause behavior changes.

If this issue lands first, we'll need to restore https://git.drupalcode.org/project/drupal/-/merge_requests/6026/diffs?co... there, if the other issue lands first, we'll need to cherry-pick that hunk over here.

The commit order doesn't matter.

I think this is looks good, it's to be expected that nothing changes in the tests yet.

Matching title of 📌 Follow-up for #3364109: opt in already validatgable simple config to FullyValidatable Active .

Committed/pushed to 11.x, thanks!

Automatically closed - issue fixed for 2 weeks with no activity.