Remove Shadow DOM Editor Attachment

Problem/Motivation

The option to attach the JSONEditor form with Shadow DOM is no longer used or maintained within the module, so the setting and related logic should be removed.

Steps to reproduce

• Navigate to /admin/config/user-interface/patternkit/json
• Observe the presence of "Use the Shadow DOM" checkbox

Proposed resolution

• Remove the "Use the Shadow DOM" setting checkbox from the settings form
• Update exported configuration to remove the setting
• Remove related JS attachment logic

Remaining tasks

User interface changes

• The "Use the Shadow DOM" setting no longer exists on the JSON Pattern Library Settings form

API changes

None

Data model changes

• The "Use the Shadow DOM" setting is removed from exported configuration