Update visual design of Infobar sample option panels

[marcelwgn]

Description

The option panels were a bit inconsistent and also resized on the options being selected. Now they have a fixed sized and the comboboxes are stretched.

Motivation and Context

Closes #1002

How Has This Been Tested?

Tested manually.

Screenshots (if appropriate):

Types of changes

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)