Collapse simplified simple_form_for to single line

[aduth]

🛠 Summary of changes

Updates form markup to collapse rendering of simple_form_for to a single line.

This is a follow-up to #10604. I had originally planned to include these changes as part of that pull request, but decided against it in order to keep the diff simpler. But the simplifications enabled by that work remove a lot of configuration from simple_form_for to allow many of them to reasonably fit within a single line of 100 column length or fewer.

📜 Testing Plan

These changes are formatting-only, so not expected to have an impact on end-user experience.