MDL-62241 privacy: Include the unit tests from the 3.3 branch

The tests do not actually do anything, they just make sure that the
method signature is correct on the given PHP version. They are mostly
relevant and useful on 3.3.

privacy/tests/manager_test.php

@@ -213,4 +213,18 @@ public function test_get_null_provider_reason() {
         $this->expectException(\coding_exception::class);
         $string = $manager->get_null_provider_reason('mod_testcomponent');
     }
+
+    /**
+     * Test that manager::plugintype_class_callback() can be executed.
+     */
+    public function test_plugintype_class_callback() {
+        \core_privacy\manager::plugintype_class_callback('doesnotexist', 'unusable', 'foo', ['bar']);
+    }
+
+    /**
+     * Test that manager::component_class_callback() can be executed.
+     */
+    public function test_component_class_callback() {
+        \core_privacy\manager::component_class_callback('foo_bar', 'unusable', 'foo', ['bar']);
+    }
 }