Shorten pusher host config (laravel#6009)

* Shorten pusher host config

* Update broadcasting.php

Co-authored-by: Taylor Otwell <[email protected]>

Author: buihanh2304

config/broadcasting.php

@@ -36,7 +36,7 @@
             'secret' => env('PUSHER_APP_SECRET'),
             'app_id' => env('PUSHER_APP_ID'),
             'options' => [
-                'host' => env('PUSHER_HOST', 'api-'.env('PUSHER_APP_CLUSTER', 'mt1').'.pusher.com') ?: 'api-'.env('PUSHER_APP_CLUSTER', 'mt1').'.pusher.com',
+                'host' => env('PUSHER_HOST') ?: 'api-'.env('PUSHER_APP_CLUSTER', 'mt1').'.pusher.com',
                 'port' => env('PUSHER_PORT', 443),
                 'scheme' => env('PUSHER_SCHEME', 'https'),
                 'encrypted' => true,