MDL-72743 tests: tidy up the new test with NS/name/covers

Ideally any new test should be using a class name matching
the file name, and to use namespace when clearly belonging to
a component (sub-namespace also allowed for better accuracy).

And, also, adding a @Covers label to indicate which class
(preferred, method is also possible) is being covered with the test.

mod/quiz/tests/restore_attempt_test.php

@@ -14,14 +14,21 @@
 // You should have received a copy of the GNU General Public License
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
+namespace mod_quiz;
+
+use backup;
+use core_user;
+use restore_controller;
+use restore_dbops;
+
 /**
  * Unit tests restoring quiz attempts
  *
  * @package     mod_quiz
  * @copyright   2021 Paul Holden <paulh@moodle.com>
  * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class mod_quiz_restore_attempt_test extends advanced_testcase {
+class restore_attempt_test extends \advanced_testcase {
 
     /**
      * Load required libraries
@@ -34,6 +41,8 @@ public static function setUpBeforeClass(): void {
 
     /**
      * Test restore dates.
+     *
+     * @covers \restore_quiz_activity_structure_step
      */
     public function test_restore_question_attempts_missing_users(): void {
         global $DB, $USER;