Plugin settings info icons are misaligned

[cndouglas]

Did you search for similar issues before submitting this one?
Yes.

Describe the issue you encountered:
The info icons in plugin settings (in Preferences) are misaligned. See the screenshot below for details.

Expected behavior:
The icons should be aligned.

• Platform (Win7, 8, 10? macOS? Linux distro?):
  Found on macOS 10.12.x

• Brave Version:
  0.12.10 release candidate 1

• Steps to reproduce:

  1. Open a new Brave window and open Preferences.
  2. Open the Security section.
  3. Look at the Plugin Settings section. Notice that the icons are misaligned.

• Screenshot if needed:
  

• Any related issues:
  Fixed missing content links for info buttons in preferences #5758 also mentions these info icons.

[luixxiul]

I'm working on it

[luixxiul]

Test plan: #6138 (as PR #5783 which closed the issue was superseded with it)