[5.8] Fix event:list command

[joedixon]

When using a combination of manually registering events in the EventServiceProvider and event auto discovery, the output of php artisan event:list can be unexpected.

Example
If I have two listeners in the app/Listeners directory for the VoteWasCast event (e.g. StoreVote and SendVote), but I only have one of those manually registered in the EventServiceProvider as below, I would still expect both to be included in the output of php artisan event:list.

class EventServiceProvider extends ServiceProvider
{
    protected $listen = [
        VoteWasCast::class => [
            StoreVote::class,
        ]
    ];
}

However, below is the output I get:

This PR provides the following output which is in line with what I would expect.

[driesvints]

Isn't it weird that the StoreVote class is now listed twice?

[joedixon]

Well, I think it’s probably expected behaviour. If I add it to the $listen array and have auto discovery on, my listener fires twice. I assume it’s the developers responsibility not to list it there and use auto discovery?

[driesvints]

@joedixon ah, if it's fired twice than that definitely makes sense. I can follow that reasoning 👍