bug symfony#53061 [Mailer] [Mailjet] Disable tls for mailjet as it should use STARTTLS (RFreij)

This PR was merged into the 6.4 branch.

Discussion
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[Mailer] [Mailjet] Disable tls for mailjet as it should use STARTTLS

| Q             | A
| ------------- | ---
| Branch?       | 6.4 <!-- see below -->
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Issues        |  <!-- prefix each issue number with "Fix #", no need to create an issue if none exists, explain below instead -->
| License       | MIT

symfony#52560 updates the default mailjet port and references the same change for mailgun.

Similar to symfony#51042 and with the same error message, the mailjet connection doesn't work now.

The PR above already has a reference, but for completion sake: Ref symfony#34846 (comment) for more explanation

Commits
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709d56f fix(mailjet-smtp): disable tls for mailjet as it should use starttls instead

Author: nicolas-grekas

src/Symfony/Component/Mailer/Bridge/Mailjet/Transport/MailjetSmtpTransport.php

@@ -19,7 +19,7 @@ class MailjetSmtpTransport extends EsmtpTransport
 {
     public function __construct(string $username, #[\SensitiveParameter] string $password, EventDispatcherInterface $dispatcher = null, LoggerInterface $logger = null)
     {
-        parent::__construct('in-v3.mailjet.com', 587, true, $dispatcher, $logger);
+        parent::__construct('in-v3.mailjet.com', 587, false, $dispatcher, $logger);
 
         $this->setUsername($username);
         $this->setPassword($password);