Fire ProxyShutdownEvent before closing the scheduler / event bus

Fixes #322

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -403,6 +403,8 @@ public class VelocityServer implements ProxyServer {
           timedOut = true;
         }
 
+        eventManager.fireShutdownEvent();
+
         timedOut = !eventManager.shutdown() || timedOut;
         timedOut = !scheduler.shutdown() || timedOut;
 
@@ -414,8 +416,6 @@ public class VelocityServer implements ProxyServer {
         Thread.currentThread().interrupt();
       }
 
-      eventManager.fireShutdownEvent();
-
       shutdown = true;
 
       if (explicitExit) {