Permit repeating WaitHandle of infinite timeout (#72267)

* Permit repeating WaitHandle of infinite timeout

* Add test for repeating waithandle with infinite timeout

Author: AaronRobinsonMSFT

src/libraries/System.Private.CoreLib/src/System/Threading/PortableThreadPool.WaitThread.cs

@@ -373,7 +373,10 @@ private void QueueWaitCompletion(RegisteredWaitHandle registeredHandle, bool tim
                 // If the handle is a repeating handle, set up the next call. Otherwise, remove it from the wait thread.
                 if (registeredHandle.Repeating)
                 {
-                    registeredHandle.RestartTimeout();
+                    if (!registeredHandle.IsInfiniteTimeout)
+                    {
+                        registeredHandle.RestartTimeout();
+                    }
                 }
                 else
                 {

src/libraries/System.Threading.ThreadPool/tests/RegisteredWaitTests.cs

@@ -126,6 +126,24 @@ public static void QueueRegisterPositiveAndFlowTest()
                     false);
             waitForBackgroundWork(true);
             Assert.Equal(0, backgroundAsyncLocalValue);
+
+            // Validate a repeating waithandle with infinite timeout.
+            registeredWaitHandle =
+                ThreadPool.UnsafeRegisterWaitForSingleObject(
+                    registerWaitEvent,
+                    (state, timedOut) =>
+                    {
+                        commonBackgroundTest(true, () =>
+                        {
+                            Assert.Same(obj, state);
+                            Assert.False(timedOut);
+                        });
+                    },
+                    obj,
+                    -1,      // Infinite
+                    false);  // Execute once
+            waitForBackgroundWork(true);
+            Assert.Equal(0, backgroundAsyncLocalValue);
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]