[Settings]Fix crash caused by dangling thread (#35603)

* Fix crash caused by dangling thread

* Fix process access to be able to WaitForSingleObject it

src/runner/settings_window.cpp

@@ -625,7 +625,7 @@ void close_settings_window()
     if (g_settings_process_id != 0)
     {
         SetEvent(g_terminateSettingsEvent);
-        wil::unique_handle proc{ OpenProcess(PROCESS_TERMINATE, false, g_settings_process_id) };
+        wil::unique_handle proc{ OpenProcess(PROCESS_ALL_ACCESS, false, g_settings_process_id) };
         if (proc)
         {
             WaitForSingleObject(proc.get(), 1500);

src/settings-ui/Settings.UI/Helpers/NativeEventWaiter.cs

@@ -4,7 +4,7 @@
 
 using System;
 using System.Threading;
-
+using System.Threading.Tasks;
 using Microsoft.UI.Dispatching;
 
 namespace Microsoft.PowerToys.Settings.UI.Helpers
@@ -14,7 +14,7 @@ namespace Microsoft.PowerToys.Settings.UI.Helpers
         public static void WaitForEventLoop(string eventName, Action callback)
         {
             var dispatcherQueue = DispatcherQueue.GetForCurrentThread();
-            new Thread(() =>
+            new Task(() =>
             {
                 var eventHandle = new EventWaitHandle(false, EventResetMode.AutoReset, eventName);
                 while (true)