Wrap plugin message copies in unreleasable copies.

Trying to track down a very weird issue that barely makes sense to me.

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java

@@ -146,7 +146,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
         .thenAcceptAsync(pme -> {
           if (pme.getResult().isAllowed() && !playerConnection.isClosed()) {
             PluginMessage copied = new PluginMessage(packet.getChannel(),
-                Unpooled.wrappedBuffer(copy));
+                Unpooled.unreleasableBuffer(Unpooled.wrappedBuffer(copy)));
             playerConnection.write(copied);
           }
         }, playerConnection.eventLoop())

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

@@ -230,7 +230,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
               server.getEventManager().fire(event).thenAcceptAsync(pme -> {
                 if (pme.getResult().isAllowed()) {
                   PluginMessage message = new PluginMessage(packet.getChannel(),
-                      Unpooled.wrappedBuffer(copy));
+                      Unpooled.unreleasableBuffer(Unpooled.wrappedBuffer(copy)));
                   backendConn.write(message);
                 }
               }, backendConn.eventLoop())