Remove opacity filter from branded providers (#1568)

-   Ticket: [ENG-3748]
-   Feature flag: n/a

## Purpose
- Remove filter on registration overview page for branded providers to help with color contrast
- Note: some providers will still not have AA compliant color contrast. To get AA compliant color contrast, we will need to change the brand's primary color that or create the ability to customize that header text 

## Summary of Changes
- Remove opacity from registration overlay

Author: futa-ikeda

lib/registries/addon/components/hero-overlay/styles.scss

@@ -30,7 +30,6 @@
 
     &::after {
         @include primary-color-bg;
-        opacity: 0.4;
         display: block;
         z-index: -1; /* should be in front of the ::before defined below */
     }