Fix D11 test errors and other compatibility errors caused by project update bot.

Closes #3434668

src/ConnectionTester/ConnectionTester.php

@@ -108,7 +108,7 @@ class ConnectionTester {
 
     $smtp_enabled = $this->smtpConfig->get('smtp_on');
     // Check to see if MailSystem is enabled and is using SMTPMailSystem.
-    if (\Drupal::moduleHandler()->moduleExists('mailsystem')) {
+    if (\Drupal::moduleHandler()->moduleExists('mailsystem')) { // @phpstan-ignore-line
       $mailsystem_defaults = (array) $this->configFactory->get('mailsystem.settings')->get('defaults');
       $smtp_enabled = in_array('SMTPMailSystem', $mailsystem_defaults);
     }