Revert "If we failed to unregister, don't fire the disconnect event"

This reverts commit 5822cc31d8.

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

@@ -291,10 +291,9 @@ public class VelocityServer implements ProxyServer {
     return true;
   }
 
-  public boolean unregisterConnection(ConnectedPlayer connection) {
-    boolean name = connectionsByName.remove(connection.getUsername().toLowerCase(Locale.US), connection);
-    boolean uuid = connectionsByUuid.remove(connection.getUniqueId(), connection);
-    return name && uuid;
+  public void unregisterConnection(ConnectedPlayer connection) {
+    connectionsByName.remove(connection.getUsername().toLowerCase(Locale.US), connection);
+    connectionsByUuid.remove(connection.getUniqueId(), connection);
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -432,10 +432,9 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     if (connectedServer != null) {
       connectedServer.disconnect();
     }
-    if (server.unregisterConnection(this)) {
+    server.unregisterConnection(this);
     server.getEventManager().fireAndForget(new DisconnectEvent(this));
   }
-  }
 
   @Override
   public String toString() {