Fix ReceiveMessageWithTimeout flaky test: increase waitTime to 1500ms and subscription propagation delay to 500ms

Agent-Logs-Url: https://github.com/zeromq/netmq/sessions/2c095c5d-19b8-4a3b-8c5c-6c70a8c34cff

Co-authored-by: drewnoakes <350947+drewnoakes@users.noreply.github.com>

Author: Copilot

src/NetMQ.Tests/SocketTests.cs

@@ -97,7 +97,7 @@ public async Task ReceiveMessageWithTimeout()
             {
                 var pubSync = new AutoResetEvent(false);
                 var payload = new byte[300];
-                const int waitTime = 500;
+                const int waitTime = 1500;
                 int port = 0;
 
                 var t1 = new Task(() =>
@@ -121,7 +121,7 @@ public async Task ReceiveMessageWithTimeout()
                     {
                         subSocket.Connect($"tcp://127.0.0.1:{port}");
                         subSocket.Subscribe("");
-                        Thread.Sleep(100);
+                        Thread.Sleep(500);
                         pubSync.Set();
 
                         NetMQMessage? msg = null;