Further cleanup of TaskAPMTest.cs

Lowered the spin duration of the tasks significantly

Author: mellinoe

src/System.Threading.Tasks/tests/Task/TaskAPMTest.cs

@@ -38,9 +38,9 @@ public sealed class TaskAPMTests : IDisposable
         private const int IntInput = 1000;
 
         /// <summary>
-        /// The constant that defines the amount time to spinwait (to simulate work) in the LongTask class
+        /// The constant that defines the number of milliseconds to spinwait (to simulate work) in the LongTask class
         /// </summary>
-        private const int LongTaskMilliseconds = 1000;
+        private const int LongTaskMilliseconds = 100;
 
         [Theory]
         [OuterLoop]