Fix flaky NoReconnectionToGatewayNotReturnedByManager test (#9942)

The test used a 1-second response timeout, which could cause legitimate
grain calls to the real gateway to spuriously timeout on slow CI machines,
leading to timeoutCount == 2 instead of the expected 1.

- Increase response timeout from 1s to 3s (still below the 5s
  OpenConnectionTimeout so fake-gateway calls still produce
  TimeoutException)
- Change timeoutCount assertion from exact equality to >= 1, since
  the core assertion is connectionCount == 1 (verifying no reconnection)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: ReubenBond

test/Orleans.Runtime.Tests/ClientConnectionTests/GatewayConnectionTests.cs

@@ -110,8 +110,10 @@ public override async Task InitializeAsync()
         [Fact, TestCategory("Functional")]
         public async Task NoReconnectionToGatewayNotReturnedByManager()
         {
-            // Reduce timeout for this test
-            this.runtimeClient.SetResponseTimeout(TimeSpan.FromSeconds(1));
+            // Use a timeout shorter than OpenConnectionTimeout (5s) so that calls to
+            // the fake gateway produce a TimeoutException, but long enough that
+            // legitimate grain calls on slow CI machines don't spuriously timeout.
+            this.runtimeClient.SetResponseTimeout(TimeSpan.FromSeconds(3));
 
             var connectionCount = 0;
             var timeoutCount = 0;
@@ -157,7 +159,7 @@ public async Task NoReconnectionToGatewayNotReturnedByManager()
 
             // Check that we only connected once to the fake GW
             Assert.Equal(1, connectionCount);
-            Assert.Equal(1, timeoutCount);
+            Assert.True(timeoutCount >= 1, $"Expected at least 1 timeout but got {timeoutCount}");
         }
 
         [Fact, TestCategory("Functional")]