* fix(symfony): drop translation command probe for object mapper

FrameworkBundle 8.2's TranslationExtractCommand extends a class of the optional symfony/translation
package, so probing it with class_exists() is a fatal error when that package is missing. The probe
only stood for "framework-bundle >= 7.3", which a composer conflict on <7.4 now guarantees, matching
the ^7.4 floor of every other Symfony dependency. Follows up #8627.

Fixes #8725

* test(symfony): guard object mapper gate test like the extension