MDL-57678 core_course: Remove padding of nbsp's on category names

Padding nested course categories by space to make them render in a tree
structure does not really make a lot of sense as they are already being
rendered as full paths. It's simpler to show them without the
indentation.

course/lib.php

@@ -637,20 +637,14 @@ function get_category_or_system_context($categoryid) {
 }
 
 /**
- * Returns full course categories trees to be used in html_writer::select()
+ * Returns the list of full course categories to be used in html_writer::select()
  *
- * Calls {@link core_course_category::make_categories_list()} to build the tree and
- * adds whitespace to denote nesting
+ * Calls {@see core_course_category::make_categories_list()} to build the list.
  *
  * @return array array mapping course category id to the display name
  */
 function make_categories_options() {
-    $cats = core_course_category::make_categories_list('', 0, ' / ');
-    foreach ($cats as $key => $value) {
-        // Prefix the value with the number of spaces equal to category depth (number of separators in the value).
-        $cats[$key] = str_repeat(' ', substr_count($value, ' / ')). $value;
-    }
-    return $cats;
+    return core_course_category::make_categories_list('', 0, ' / ');
 }
 
 /**