I show the same changes in spacing from Online version 9.2 to 9.3.
There is no way to alter the layout of the site itself.
You can submit an Idea on the community forums for additional layout features if you wish.
Use this link to submit an idea change to our Developers. https://community.tableau.com/community/ideas
it's a fine line, but I see this more so as a bug in the UI that will prevent upgrading to prod; rather than a feature to be included somewhere deep in the future as an idea. Just my 2 cents