There is no reason to continue if we DC a player during shutdown

Thanks Ice

Spigot-Server-Patches/Block-player-logins-during-server-shutdown.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Block player logins during server shutdown
 
 
 diff --git a/src/main/java/net/minecraft/server/LoginListener.java b/src/main/java/net/minecraft/server/LoginListener.java
-index 2158fcd3..2367023c 100644
+index 2158fcd32..c5434e6ba 100644
 --- a/src/main/java/net/minecraft/server/LoginListener.java
 +++ b/src/main/java/net/minecraft/server/LoginListener.java
 @@ -0,0 +0,0 @@ public class LoginListener implements PacketLoginInListener, ITickable {
@@ -15,6 +15,7 @@ index 2158fcd3..2367023c 100644
 +        // Paper start - Do not allow logins while the server is shutting down
 +        if (!MinecraftServer.getServer().isRunning()) {
 +            this.disconnect(new ChatMessage(org.spigotmc.SpigotConfig.restartMessage));
++            return;
 +        }
 +        // Paper end
          if (this.g == LoginListener.EnumProtocolState.READY_TO_ACCEPT) {