Small improvement of the run test page

[hannaeko]

Purpose

Primarily to fix some contrast issues and avoid moving content.

Context

-

Changes

• Change the color of the "Run" button from red to blue (fix contrast issue)
• Move undelegated test notice in advanced options (avoid form to move down when advanced options are opened, is visually closer to the related content)
• Change link style in undelegated test notice (fix contrast issue)
• Add a decorative "Info" icon in undelegated test notice
• Slightly change the color of the advanced options toggle to match the "Run" button

How to test this PR

• Looking for contrast issues on the "Run test" page (with advanced options open) using e.g. the Firefox dev tool should return nothing
• Checking that the undelegated test notice is present but has moved inside the advanced options

[ghost]

v2023.1 release testing

Works as expected:

• using the browser's accessibility tool, I see no error related to color contrast.
• the undelegated test notice block has moved into the option section.