LPS-48423 Buttons misaligned or cut off in DDL Documents and Media field

Hi @jonmak08,

Here is an update for https://issues.liferay.com/browse/LPS-48423.

This issue is caused by this line https://github.com/liferay/liferay-portal/blame/master/portal-web/docroot/html/portlet/dynamic_data_lists/css/main.css#L20, which is added for [LPS-43385](https://issues.liferay.com/browse/LPS-43385). I simply removed it since input field and button are now on separate lines, and this won't cause regression.

Please let me know if there's any issues. Thanks!