MDL-83718 reportbuilder: use aliased user fullname sort fields.

This is extending work started in 8f32e623 that removed duplicate
fields when sorting user fullname columns (to ensure compatibility
across supported DBs).

We must now refer to these sorted fields by their alias in order to
ensure they continue working when processed from the report table.

Co-authored-by: David Carrillo <davidmc@moodle.com>

reportbuilder/classes/table/base_report_table.php

@@ -214,7 +214,7 @@ abstract class base_report_table extends table_sql implements dynamic, renderabl
      */
     public function get_sql_sort() {
         $columnsbyalias = $this->report->get_active_columns_by_alias();
-        $columnsortby = [];
+        $columnsortby = $columnsortbyalias = [];
 
         // First pass over sorted columns, to extract all the fullname fields from table_sql.
         $sortedcolumns = $this->get_sort_columns();
@@ -239,14 +239,20 @@ abstract class base_report_table extends table_sql implements dynamic, renderabl
         }
 
         // Now ensure that any fullname sorted columns have duplicated aliases removed.
-        $columnsortby = array_filter($columnsortby, static function(string $alias) use ($sortedcolumnsfullname): bool {
-            if (preg_match('/^c[\d]+_(?<column>.*)$/', $alias, $matches)) {
-                return !array_key_exists($matches['column'], $sortedcolumnsfullname);
+        foreach ($columnsortby as $sortfield => $dir) {
+            if (array_key_exists($sortfield, $sortedcolumnsfullname)) {
+                $sortfieldalias = array_filter(
+                    $columnsortby,
+                    fn(string $key) => preg_match("/^c[\d]+_{$sortfield}$/", $key),
+                    ARRAY_FILTER_USE_KEY,
+                );
+                $columnsortbyalias[array_key_first($sortfieldalias)] = $dir;
+            } else if (!array_key_exists($sortfield, $columnsortbyalias)) {
+                $columnsortbyalias[$sortfield] = $dir;
             }
-            return true;
-        }, ARRAY_FILTER_USE_KEY);
+        }
 
-        return static::construct_order_by($columnsortby);
+        return static::construct_order_by($columnsortbyalias);
     }
 
     /**