Revert "Decouple XModule styles from LMS/Studio styles (attempt 2) (#32188)" (#32191)

This reverts commit c34f8efc0e.

xmodule/css/editor/edit.scss

@@ -1,9 +1,3 @@
-@import 'vendor/bi-app/bi-app-ltr';
-@import 'bourbon/bourbon';
-@import 'lms/theme/variables';
-@import 'cms/theme/variables-v1';
-@import 'mixins';
-
 // This is shared CSS between the xmodule problem editor and the xmodule HTML editor.
 .editor {
   position: relative;