[DrupalImage] Adopt CKEditor 5 36's performance optimization: lazily instantiate contextual balloons

Problem/Motivation

Follow-up for 📌 Update CKEditor 5 to 36.0.1 Fixed .

See https://github.com/ckeditor/ckeditor5/commit/c276c45a934e4ad7c2a8ccd0bd9.... We need to adopt this in DrupalImage too.

Steps to reproduce

N/A

Proposed resolution

Adopt the same pattern as they used upstream in https://github.com/ckeditor/ckeditor5/commit/c276c45a934e4ad7c2a8ccd0bd9....

Remaining tasks

Do it!

User interface changes

CKEditor 5 starts slightly faster!

API changes

None.

Data model changes

None.

Release notes snippet

TBD