[MM-37090] Update loading screen branding (#1706)

* update loading screen branding

- background
- logo light mode colour

* linting

* build mac installer on pr

* use the actual branch name

.circleci/config.yml

@@ -449,8 +449,6 @@ workflows:
             branches:
               only:
                 - /^release-\d+(\.\d+){1,2}(-rc.*)?/
-                - MM-36793
-
       - store_artifacts:
           # for master/PR builds
           requires: