Increase the color contrast of the iconography on the status report page

Problem/Motivation

The yellow icon has a too low color contrast against the white background in light mode (See the table in https://docs.google.com/spreadsheets/d/1won35PxhRFexJYE8FmZ4DCNTo7xEAxC8... or iconography.xlsx.zip → for more details).

Discussed and iterated on the issue with @mgifford, @the_g_bomb, @katannshaw, and @drupa11y

Steps to reproduce

• Go to admin/reports/status

Proposed resolution

• Increase the color contrast to at least 3:1 for the color yellow against the background layer used in warning messages in light mode so it meets SC1.4.11.

Remaining tasks

User interface changes

API changes

Data model changes