Cron service is no longer lazy and proxy class is removed

The cron service is no longer marked lazy, and its proxy Drupal\Core\ProxyClass\Cron has been removed. Instead, if cron needs to be injected into a service, it is recommended to use service closures instead.

If existing code injecting the cron service is not updated, there may be a slight performance hit due to the different ways that lazy services/proxy classes and service closures optimize for late instantiation (generally 1ms or less). Otherwise, existing code should continue to function as usual.

Before:

public function __construct(
  protected CronInterface $cron,
) {}

Service definition:

services:
  my_service:
    class: Foo\Bar
    arguments: ['@cron']

After:

public function __construct(
  protected \Closure $cronClosure,
) {}

protected function getCron(): CronInterface {
  return ($this->cronClosure)();
}

Service definition:

services:
  my_service:
    class: Foo\Bar
    arguments: [!service_closure '@cron']

Service closures can also be autowired.
Before:

public function __construct(
  protected CronInterface $cron,
) {}

Service definition:

services:
  my_service:
    class: Foo\Bar
    autowire: true

After:

use Symfony\Component\DependencyInjection\Attribute\AutowireServiceClosure;

public function __construct(
  #[AutowireServiceClosure('cron')]
  protected \Closure $cronClosure,
) {}

protected function getCron(): CronInterface {
  return ($this->cronClosure)();
}