Management: Index Pattern directory rename / correction (#26858) (#27102)

* correct directory name

* fix scss reference

src/legacy/core_plugins/kibana/public/management/index.scss

@@ -12,4 +12,4 @@
 // Core
 @import 'management_app';
 @import 'sections/settings/advanced_settings';
-@import 'sections/indices/index';
+@import 'sections/index_patterns/index';

src/legacy/core_plugins/kibana/public/management/sections/index.js

@@ -19,4 +19,4 @@
 
 import './settings';
 import './objects';
-import './indices';
+import './index_patterns';