Fix (icon search popover): clear icon button reverts to default icon

[mxkae]

fixes #3348

[github-actions[bot]]

🤖 Pull request artifacts

file	commit
pr3359-stackable-3359-merge.zip	8a7cebc7d94210f2160bdcc39b3d8f791aeca2f9

[github-actions[bot]]

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://raw.githubusercontent.com/gambitph/Stackable/artifacts/pr3359-stackable-3359-merge.zip"}}]}