Refactor getMailerMessage to use getMailerEvent

Replaced the O(N) operation of fetching all mailer messages to find one by index with an O(1) operation by fetching the specific event first. This avoids unnecessary memory allocation for the messages array.

Author: TavoNiievez

src/Codeception/Module/Symfony/MailerAssertionsTrait.php

@@ -198,7 +198,9 @@ public function getMailerMessages(?string $transport = null): array
      */
     public function getMailerMessage(int $index = 0, ?string $transport = null): ?RawMessage
     {
-        return $this->getMailerMessages($transport)[$index] ?? null;
+        $event = $this->getMailerEvent($index, $transport);
+
+        return $event?->getMessage();
     }
 
     protected function grabLastSentRawMessage(): ?RawMessage

tests/_app/Message/TestMessage.php

@@ -8,8 +8,7 @@ final class TestMessage
 {
     public function __construct(
         private readonly string $content = '',
-    ) {
-    }
+    ) {}
 
     public function getContent(): string
     {