[controller] Don't release admin on failed rendezvous (#5300)

Admin ID is released on failed rendezvous session although
it's only assigned once during the device controller
initialization. As a result, it's impossible to pair another
device if the previous rendezvous returned an error.

Release the admin on the device controller shutdown, instead.

src/controller/CHIPDeviceController.cpp

@@ -210,6 +210,8 @@ CHIP_ERROR DeviceController::Shutdown()
         mTransportMgr = nullptr;
     }
 
+    mAdmins.ReleaseAdminId(mAdminId);
+
     ReleaseAllDevices();
     return CHIP_NO_ERROR;
 }

src/transport/RendezvousSession.cpp

@@ -322,17 +322,9 @@ void RendezvousSession::UpdateState(RendezvousSession::State newState, CHIP_ERRO
             mTransport = nullptr;
         }
 
-        if (CHIP_NO_ERROR != err)
+        if (CHIP_NO_ERROR != err && mDelegate != nullptr)
         {
-            if (mAdmin != nullptr)
-            {
-                mAdmin->Reset();
-            }
-
-            if (mDelegate)
-            {
-                mDelegate->OnRendezvousError(err);
-            }
+            mDelegate->OnRendezvousError(err);
         }
         break;