Clean up org pages layout (#37445)

1. Fix overview sidebar regression
2. Remove unnecessary classes and styles
3. Fix "org invite" page

web_src/css/index.css

@@ -37,7 +37,6 @@
 
 @import "./shared/flex-list.css";
 @import "./shared/milestone.css";
-@import "./shared/repoorg.css";
 @import "./shared/settings.css";
 
 @import "./features/dropzone.css";