MDL-74413 phpunit: Move more tests to use correct names and namespaces

Applied the following changes to various testcase classes:

- Namespaced with component[\level2-API]
- Moved to level2-API subdirectory when required.
- Fixed incorrect use statements with leading backslash.
- Remove file phpdoc block
- Remove MOODLE_INTERNAL if not needed.
- Changed code to point to global scope when needed.
- Fix some relative paths and comments here and there.
- All them passing individually.
- Complete runs passing too.

Special mention to:

- Moved to the level2 "privacy" namespace:
  - \mod_assign\privacy\feedback_legacy_polyfill_test
  - \mod_assign\privacy\submission_legacy_polyfill_test

- Moved to the level2 "task" namespace:
  - \core_message\task\migrate_message_data_test
  - \ltiservice_gradebookservices\task\cleanup_test
  - \message_email\task\send_email_test
  - \mod_lti\task\clean_access_tokens_test
  - \mod_workshop\task\cron_task_test

- Moved to the level2 "event" namespace:
  - \core_h5p\event\deleted_test
  - \core_h5p\event\viewed_test

- Renamed to a better name:
  - backup_forum_activity_task_test.php (missing "task")

grade/tests/querylib_test.php

@@ -14,14 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
-/**
- * Unit tests for grade quering
- *
- * @package   core_grades
- * @category  phpunit
- * @copyright 2011 Petr Skoda {@link http://skodak.org}
- * @license   http://www.gnu.org/copyleft/gpl.html GNU Public License
- */
+namespace core_grades;
 
 defined('MOODLE_INTERNAL') || die();
 
@@ -29,8 +22,15 @@ global $CFG;
 require_once($CFG->libdir.'/gradelib.php');
 require_once($CFG->dirroot.'/grade/querylib.php');
 
-
-class core_grade_querylib_testcase extends advanced_testcase {
+/**
+ * Unit tests for grade quering
+ *
+ * @package   core_grades
+ * @category  test
+ * @copyright 2011 Petr Skoda {@link http://skodak.org}
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU Public License
+ */
+class querylib_test extends \advanced_testcase {
 
     public function test_grade_get_gradable_activities() {
         $this->resetAfterTest(true);