fix(symfony): guard browserkit verbose setter on symfony 6.4

[ousamabenyounes]

Q	A
Branch?	4.3
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	Fix #8564
License	MIT

Summary

Since 4.3.19 (#8523) ApiTestCase registers a #[Before] hook calling self::setBrowserKitAssertionsAsVerbose(true). That setter only exists since Symfony 7.3, so on Symfony 6.4 — a combination Composer still allows on 4.3 — every ApiTestCase-based test fatals with Call to undefined method before its body runs. No CI job caught it: the root PHPUnit suite is the only one exercising ApiTestCase and it always installs Symfony >= 7.x.

The call is now guarded with method_exists(): verbose output stays on where the setter exists, and is a no-op where it does not. PHPStan analyses against Symfony 8.1, where the setter always exists, so the guard is reported as function.alreadyNarrowedType; it carries a one-line @phpstan-ignore next to the BC reason, like the other Symfony BC guards already ignored in phpstan.neon.dist.

Test plan

• symfony/framework-bundle 6.4.46 — method_exists(BrowserKitAssertionsTrait::class, 'setBrowserKitAssertionsAsVerbose') is false, confirming the guard is required.
• vendor/bin/phpstan analyse src/Symfony/Bundle/Test/ApiTestCase.php — 1 error before the ignore, 0 after (Symfony 8.1.7, PHPStan 2.x).
• PHP_CS_FIXER_IGNORE_ENV=1 vendor/bin/php-cs-fixer fix src/Symfony/Bundle/Test/ApiTestCase.php — clean.
• vendor/bin/phpunit tests/Symfony/Bundle/Test — 67 tests, 109 assertions, 3 failures, identical to the same run on origin/4.3 (local sqlite fixture schema, unrelated to this change).
• commitlint -g .commitlintrc on the branch's single commit — green.

[soyuka]

Please target 4.4 or 5.0

[ousamabenyounes]

Rebased onto 4.4 and retargeted, thanks @soyuka.

[soyuka]

phpstan is red you can lower the amount of comments as well

[ousamabenyounes]

@soyuka thanks — both addressed.

PHPStan: the guard is unavoidably "always true" under Symfony 8.1 (I tried self::class, the BrowserKitAssertionsTrait name, Kernel::VERSION_ID, and is_callable — all narrowed), so it now carries a one-line @phpstan-ignore function.alreadyNarrowedType with the BC reason, like the other Symfony BC guards already ignored in phpstan.neon.dist. Green on the changed file.

Comments: the 4 added docblock lines are gone, one inline line left. Commit rebased on 4.3 with a single scope and a shorter subject, which also fixes commitlint (it was linting an unrelated commit picked up from a wrong merge base).