This PR was merged into the 4.3 branch.

Discussion
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[TwigBundle] Fix Mailer integration in Twig

| Q             | A
| ------------- | ---
| Branch?       | 4.3
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #31449
| License       | MIT
| Doc PR        | n/a

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Commits
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53b68af [TwigBundle] fixed Mailer integration in Twig