Remove deprecated ckeditor5_list.properties.styles config key for Drupal 10.6+ compatibility

Problem/Motivation

Drupal core 10.6+ no longer supports the styles key under ckeditor5_list.properties. Keeping this deprecated configuration causes configuration validation errors during installation or configuration import.

The issue manifests with the following error:

settings.plugins.ckeditor5_list.properties.styles: 'styles' is not a supported key.

This prevents successful installs or config syncs on Drupal 10.6 and newer.

Proposed resolution

Remove the deprecated styles: false entry from ckeditor5_list.properties in the affected configuration file.

This aligns the configuration with current Drupal core CKEditor 5 schema requirements.
Removing this key is safe and backward-compatible, as the property is no longer used or supported by Drupal core.

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ➖ UX/UI designer responsibilities
• ➖ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-10.0.9, varbase_editor-10.0.21

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• fix: #3565819 Remove deprecated ckeditor5_list.properties.styles config key for Drupal 10.6+ compatibility