Fix the H5P unit tests for php74

We have lots of tests in H5P component failing because the classes apparently cannot be found, so somehow the autoloader is at fault / not run.

Error: Class 'core_h5p\framework' not found

/var/www/html/h5p/classes/factory.php:76

/var/www/html/h5p/tests/framework_test.php:48

/var/www/html/lib/phpunit/classes/advanced_testcase.php:80

Link: https://ci.moodle.org/view/Testing/job/DEV.74%20-%20PHPUnit%207.4%20-%20MDL-66260/8/

It could be the autoloader has not been invoked and all tests fail because of that.

More details: https://tracker.moodle.org/browse/MDL-66609?focusedCommentId=707888&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-707888