MDL-72743 phpunit: Skip test until MDL-72950 is fixed

It's good to keep the test because it's not easy to
reproduce the issue to be fixed. Part of the fix will
be to remove this skip.

mod/quiz/tests/restore_attempt_test.php

@@ -47,6 +47,11 @@ class restore_attempt_test extends \advanced_testcase {
     public function test_restore_question_attempts_missing_users(): void {
         global $DB, $USER;
 
+        // TODO: Remove this once MDL-72950 is fixed.
+        if ($DB->get_dbfamily() == 'oracle') {
+            $this->markTestSkipped("Skipping for Oracle until MDL-72950 is fixed.");
+        }
+
         $this->resetAfterTest();
         $this->setAdminUser();