[Privatization] Skip Symfony Command protected static property in PrivatizeFinalClassPropertyRector

[TomasVotruba]

PrivatizeFinalClassPropertyRector must keep a protected static property that is declared on a parent class. Symfony console commands are the common real-world case:

use Symfony\Component\Console\Command\Command;

final class SendWinnerEmailCommand extends Command
{
    protected static $defaultDescription = 'Send winner email variant to remaining contacts';
}

Command declares protected static $defaultDescription, so privatizing the child override would break the parent contract. The property must stay protected (unchanged).

The ParentPropertyLookupGuard already guards this via hasStaticProperty(); this PR adds a fixture locking the behavior against a real Symfony\Component\Console\Command\Command parent.