Write performance test for ckeditors

Problem/Motivation

Found during ✨ Pages with multiple instances on CKEditor 5 are unnecessary slow Active it seemed out of scope to add performance test coverage in that issue so opening this

Steps to reproduce

N/A

Proposed resolution

Add performance coverage for ckeditor5

Remaining tasks

Do it

User interface changes

N/A

Introduced terminology

N/A

API changes

N/A

Data model changes

N/A

Release notes snippet

N/A