Change layout of throttling settings form from horizontal to vertical

[mturley]

Associated RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1701376

Originally part of feedback for #915, I merged that PR so we could make sure it ended up in Monday's build. This PR only changes the layout of the settings form.

[miq-bot]

Checked commits mturley/manageiq-v2v@28263ff~...fee3bee with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
0 files checked, 0 offenses detected
Everything looks fine. ⭐

[simaishi]

@mturley Backport conflicts... can you please create a separate PR for hammer branch?

$ git status
On branch hammer
Your branch is up to date with 'origin/hammer'.

You are currently cherry-picking commit 5b858417.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:

	modified:   app/javascript/react/screens/App/Settings/Settings.scss
	modified:   app/javascript/react/screens/App/common/forms/TextInputWithCheckbox.js

Unmerged paths:
  (use "git add <file>..." to mark resolution)

	both modified:   app/javascript/react/screens/App/Settings/screens/GeneralSettings/GeneralSettings.js
	both modified:   app/javascript/react/screens/App/Settings/screens/GeneralSettings/__tests__/__snapshots__/GeneralSettings.test.js.snap

[mturley]

@simaishi here's the hammer-specific PR: #945

[simaishi]

Backported to Hammer via #945