Remove redundant $service variable in case of simply service without dependencies.

[janbarasek]

In case of:

public function createServiceMyService(): Model\MyService
{
	$service = new Model\MyService;
	return $service;
}

Generate simplify version:

public function createServiceMyService(): Model\MyService
{
	return new Model\MyService;
}

And in case of simple static service:

public function createServiceMyService(): Model\MyService
{
	$service = Model\MyServiceFactory::getInstance();
	return $service;
}

Generate:

public function createServiceMyService(): Model\MyService
{
	return Model\MyServiceFactory::getInstance();
}

[dg]

I think it would be cleaner to deal with this in ServiceDefinition::generateMethod()…