Make changes needed after the fix of MDL-83541

[PhilippImhof]

With the fix of MDL-83541, Moodle will calculate a hash of all relevant fields of a question and its answers during the restore process. This allows to avoid duplicating questions during imports while still being able to distinguish different questions with the same "stamp".

This PR makes the necessary changes.

It can be tested using the mod/quiz/tests/backup/repeated_restore_test.php unit tests in Moodle 4.5 and upcoming 5.0. You may want to tweak the test a bit by changing its get_qtype_generators() data provider and adding

$generators = [
            ['pmatch', 'listen'],
            ['pmatch', 'frogtoad'],
            ['pmatch', 'spanish'],
        ];

at the end, in order to just check this question type (instead of all installed types) and to make sure it uses the three questions with a get_pmatch_question_form_data_* method, instead of just the first one that can be found.