MDL-81521 core: Update all possibly data providers to be static

Note: Some data providers could not be automatically be converted to
being static. These will be handled in a separate issue.

analytics/tests/indicator_test.php

@@ -29,8 +29,7 @@ require_once(__DIR__ . '/fixtures/test_indicator_min.php');
  * @copyright 2017 David Monllaó {@link http://www.davidmonllao.com}
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class indicator_test extends \advanced_testcase {
-
+final class indicator_test extends \advanced_testcase {
     /**
      * test_validate_calculated_value
      *
@@ -50,7 +49,7 @@ class indicator_test extends \advanced_testcase {
      *
      * @return array
      */
-    public function validate_calculated_value() {
+    public static function validate_calculated_value(): array {
         return [
             'max' => ['test_indicator_max', [1]],
             'min' => ['test_indicator_min', [-1]],
@@ -83,7 +82,7 @@ class indicator_test extends \advanced_testcase {
      *
      * @return array
      */
-    public function validate_calculated_value_exceptions() {
+    public static function validate_calculated_value_exceptions(): array {
         return [
             'max' => ['test_indicator_max', 2],
             'min' => ['test_indicator_min', -2],