[Silabs][WiFi] CNET 4.4 test step fix for NetworkNotFound (#32729)

* adding the network not found fix for cnet

* Restyled by clang-format

* modifying it to be guard style

* Restyled by clang-format

---------

Co-authored-by: Restyled.io <[email protected]>

Author: chirag-silabs

src/platform/silabs/NetworkCommissioningWiFiDriver.cpp

@@ -278,6 +278,15 @@ void SlWiFiDriver::OnScanWiFiNetworkDone(wfx_wifi_scan_result_t * aScanResult)
     {
         if (GetInstance().mpScanCallback != nullptr)
         {
+            if (mScanResponseIter.Count() == 0)
+            {
+                // if there is no network found, return kNetworkNotFound
+                DeviceLayer::SystemLayer().ScheduleLambda([]() {
+                    GetInstance().mpScanCallback->OnFinished(NetworkCommissioning::Status::kNetworkNotFound, CharSpan(), nullptr);
+                    GetInstance().mpScanCallback = nullptr;
+                });
+                return;
+            }
             DeviceLayer::SystemLayer().ScheduleLambda([]() {
                 GetInstance().mpScanCallback->OnFinished(NetworkCommissioning::Status::kSuccess, CharSpan(), &mScanResponseIter);
                 GetInstance().mpScanCallback = nullptr;