fix(mongo): make client reconnect test more robust

The test was flaky because await sleep(0) doesn't always give enough
time for TCP close events to propagate through the event loop,
especially under CPU contention when multiple CI runners execute
jobs in parallel.

Now waits up to 1 second for the connection to actually close.

Author: marcj

packages/mongo/tests/client/mong-env.spec.ts

@@ -100,7 +100,10 @@ describe('mongo-env', () => {
         }
 
         mongo.closeConnections();
-        await sleep(0);
+        // Wait for close event to propagate (may take a few event loop ticks under load)
+        for (let i = 0; i < 100 && client.pool.isConnected(); i++) {
+            await sleep(0.01);
+        }
         expect(client.pool.isConnected()).toBe(false);
 
         {