Don't try to establish PASE while we are shutting down. (#20706)

Shutdown of a DeviceCommissioner needs to suppress the "try the next
discovered thing on error" behavior of SetUpCodePairer.

Fixes #20271

src/controller/CHIPDeviceController.cpp

@@ -466,6 +466,8 @@ void DeviceCommissioner::Shutdown()
 
     ChipLogDetail(Controller, "Shutting down the commissioner");
 
+    mSetUpCodePairer.CommissionerShuttingDown();
+
     // Check to see if pairing in progress before shutting down
     CommissioneeDeviceProxy * device = mDeviceInPASEEstablishment;
     if (device != nullptr && device->IsSessionSetupInProgress())

src/controller/SetUpCodePairer.cpp

@@ -308,6 +308,11 @@ void SetUpCodePairer::NotifyCommissionableDeviceDiscovered(const Dnssd::Discover
     ConnectToDiscoveredDevice();
 }
 
+void SetUpCodePairer::CommissionerShuttingDown()
+{
+    ResetDiscoveryState();
+}
+
 bool SetUpCodePairer::TryNextRendezvousParameters()
 {
     if (ConnectToDiscoveredDevice())

src/controller/SetUpCodePairer.h

@@ -72,6 +72,10 @@ class DLL_EXPORT SetUpCodePairer : public DevicePairingDelegate
     void SetBleLayer(Ble::BleLayer * bleLayer) { mBleLayer = bleLayer; };
 #endif // CONFIG_NETWORK_LAYER_BLE
 
+    // Called to notify us that the DeviceCommissioner is shutting down and we
+    // should not try to do any more new work.
+    void CommissionerShuttingDown();
+
 private:
     // DevicePairingDelegate implementation.
     void OnStatusUpdate(DevicePairingDelegate::Status status) override;