fix: studio edx.org-next theme

Attaching jira ticket for reference: https://2u-internal.atlassian.net/browse/TNL-11731

- compile_sass script was generating the `studio-main-v1.scss` file but it wasn't correct and wasn't picking the changes from paragon. As a result, `edx.org-next` theme wasn't being applied to the studio. And the reason was this line: https://github.com/openedx/edx-platform/pull/35233/files#:~:text=//%20%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D%3D-,%40import%20%27_builtin%2Dblock%2Dvariables%27%3B,-%40import%20%27bourbon.
- This PR fixes the studio theme as I have rearranged `studio-main-v1.scss` file so that theme changes can be applied correctly.

cms/static/sass/studio-main-v1.scss

@@ -16,7 +16,7 @@
 // +Libs and Resets - *do not edit*
 // ====================
 
-@import '_builtin-block-variables';
 @import 'bourbon/bourbon'; // lib - bourbon
 @import 'vendor/bi-app/bi-app-ltr'; // set the layout for left to right languages
 @import 'build-v1'; // shared app style assets/rendering
+@import '_builtin-block-variables';