fix (icon list): editor freezes when adding patterns with icon list

[kaeizen]

fixes #3332

[github-actions]

🤖 Pull request artifacts

file	commit
pr3333-stackable-3333-merge.zip	8cf3708

[github-actions]

Try this Pull Request in the WordPress playground: https://playground.wordpress.net/?mode=seamless#{"landingPage":"/wp-admin/post-new.php?post_type=page","preferredVersions":{"php":"latest","wp":"latest"},"steps":[{"step":"login","username":"admin","password":"password"},{"step":"installPlugin","pluginZipFile":{"resource":"url","url":"https://github.com/ghraw/gambitph/Stackable/artifacts/pr3333-stackable-3333-merge.zip"}}]}