Callback before_footer in local_mandatory_courses component should be migrated to new hook callback for core\hook\output\before_footer_html_generation

• line 7263 of /lib/moodlelib.php: call to debugging()
• line 7330 of /lib/moodlelib.php: call to {closure}()
• line 71 of /lib/classes/hook/output/before_footer_html_generation.php: call to get_plugins_with_function()
• line 988 of /lib/classes/output/core_renderer.php: call to core\hook\output\before_footer_html_generation->process_legacy_callbacks()
• line 515 of /login/index.php: call to core\output\core_renderer->footer()