UserInstallTest testUserInstall() custom assert message not more helpful than the default.

Problem/Motivation

Noticed by @alexpott in #2340667-45: Protect Drupal\Core\Language\Language::id, and use getId()

+++ b/core/modules/user/src/Tests/UserInstallTest.php
@@ -47,8 +47,8 @@ public function testUserInstall() {
-    $this->assertEqual($anon->langcode, \Drupal::languageManager()->getDefaultLanguage()->id);
-    $this->assertEqual($admin->langcode, \Drupal::languageManager()->getDefaultLanguage()->id);
+    $this->assertEqual($anon->langcode, \Drupal::languageManager()->getDefaultLanguage()->getId(), 'Anon user language is the default.');
+    $this->assertEqual($admin->langcode, \Drupal::languageManager()->getDefaultLanguage()->getId(), 'Admin user language is the default.');

The test assertion message here is less useful to a developer than the default - which would tell you what the two langcodes are.

Proposed resolution

Take out the custom assert message.

Remaining tasks

User interface changes

No.

API changes

No.