[set] remove unused version-based-set constants and configs

[TomasVotruba]

Use ->withComposerBased(symfony: true) instead: https://getrector.com/documentation/composer-based-sets

Ref rectorphp/rector-src#7877

Before

Every Symfony version set had to be listed by hand, and each one had to be kept in sync with the very same configuration in composer-based.php:

return RectorConfig::configure()
    ->withSets([
        SymfonySetList::SYMFONY_25,
        SymfonySetList::SYMFONY_26,
        SymfonySetList::SYMFONY_27,
        SymfonySetList::SYMFONY_28,
        SymfonySetList::SYMFONY_30,
        SymfonySetList::SYMFONY_31,
        SymfonySetList::SYMFONY_32,
        SymfonySetList::SYMFONY_33,
        SymfonySetList::SYMFONY_34,
        SymfonySetList::SYMFONY_40,
        // ...and 23 more, up to SYMFONY_81
    ]);

After

The installed Symfony package versions pick the rules:

return RectorConfig::configure()
    ->withComposerBased(symfony: true);

What changed

• 195 per-version set files removed, their configuration is already in config/sets/symfony/composer-based.php, bound to the exact package version it was introduced in
• the matching SymfonySetList::SYMFONY_* constants removed
• tests/Set/Symfony* suites removed - the rules and the composer-based set are the source of truth and have their own tests