minor #29210 [Messenger] Fix typos (ogizanagi)

This PR was merged into the 4.2-dev branch.

Discussion
----------

[Messenger] Fix typos

| Q             | A
| ------------- | ---
| Branch?       | 4.2 <!-- see below -->
| Bug fix?      | no
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | N/A   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | N/A

Just small typos extracted from #29166 in case it doesn't make it to 4.2.

Commits
-------

7e763f96c1 [Messenger] Fix typos

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -1583,7 +1583,7 @@ class FrameworkExtension extends Extension
             }, $messageConfiguration['senders']);
 
             $sendersId = 'messenger.senders.'.$message;
-            $sendersDefinition = $container->register($sendersId, RewindableGenerator::class)
+            $container->register($sendersId, RewindableGenerator::class)
                 ->setFactory('current')
                 ->addArgument(array(new IteratorArgument($senders)));
             $messageToSendersMapping[$message] = new Reference($sendersId);

src/Symfony/Component/Messenger/Stamp/ReceivedStamp.php

@@ -14,7 +14,7 @@ namespace Symfony\Component\Messenger\Stamp;
 use Symfony\Component\Messenger\Middleware\SendMessageMiddleware;
 
 /**
- * Marker config for a received message.
+ * Marker stamp for a received message.
  *
  * This is mainly used by the `SendMessageMiddleware` middleware to identify
  * a message should not be sent if it was just received.

src/Symfony/Component/Messenger/Tests/EnvelopeTest.php

@@ -39,7 +39,7 @@ class EnvelopeTest extends TestCase
         $this->assertNotSame($envelope, $envelope->with(new ReceivedStamp()));
     }
 
-    public function testGetLast()
+    public function testLast()
     {
         $receivedStamp = new ReceivedStamp();
         $envelope = new Envelope($dummy = new DummyMessage('dummy'), $receivedStamp);