fix: remove custom css for help sidebar

Author: rpenido

src/library-authoring/import-course/HelpSidebar.tsx

@@ -6,7 +6,7 @@ import { Paragraph } from '@src/utils';
 import messages from './messages';
 
 export const HelpSidebar = () => (
-  <div className="course-migration-help pt-3 border-left">
+  <div className="pt-3 border-left">
     <Stack gap={1} direction="horizontal" className="pl-4 h4 text-primary-700">
       <Icon src={Question} />
       <span>

src/library-authoring/import-course/index.scss

@@ -1,17 +1,3 @@
-.course-migration-help {
-  z-index: 1000; // same as header
-  flex: 350px 0 0;
-  position: sticky;
-  top: 0;
-  right: 0;
-  height: 100vh;
-  overflow-y: auto;
-
-  hr {
-    width: 100%;
-  }
-}
-
 .status-border-imported {
   border-left: 8px solid #5690BB;
 }