Clean up stale debugger-related surface area in ThreadPool and Task{Scheduler}

src/libraries/System.Private.CoreLib/src/ILLink/ILLink.Descriptors.Shared.xml

@@ -32,14 +32,9 @@
   <assembly fullname="System.Private.CoreLib" feature="System.Diagnostics.Debugger.IsSupported" featurevalue="true" featuredefault="true">
     <type fullname="System.Threading.Tasks.Task">
       <property name="ParentForDebugger" />
-      <property name="StateFlagsForDebugger" />
-      <property name="StateFlags" />
       <method name="GetDelegateContinuationsForDebugger" />
       <method name="SetNotificationForWaitCompletion" />
     </type>
-    <type fullname="System.Threading.Timer">
-      <property name="AllTimers" />
-    </type>
     <type fullname="System.Threading.Tasks.TaskScheduler">
       <method name="GetScheduledTasksForDebugger" />
       <method name="GetTaskSchedulersForDebugger" />

src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs

@@ -130,8 +130,6 @@ public class Task : IAsyncResult, IDisposable
         internal volatile int m_stateFlags; // SOS DumpAsync command depends on this name
 
         private Task? ParentForDebugger => m_contingentProperties?.m_parent; // Private property used by a debugger to access this Task's parent
-        private int StateFlagsForDebugger => m_stateFlags; // Private property used by a debugger to access this Task's state flags
-        private TaskStateFlags StateFlags => (TaskStateFlags)(m_stateFlags & ~(int)TaskStateFlags.OptionsMask); // Private property used to help with debugging
 
         [Flags]
         internal enum TaskStateFlags

src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/TaskScheduler.cs

@@ -218,12 +218,6 @@ internal virtual void NotifyWorkItemProgress()
         {
         }
 
-        /// <summary>
-        /// Indicates whether this is a custom scheduler, in which case the safe code paths will be taken upon task entry
-        /// using a CAS to transition from queued state to executing.
-        /// </summary>
-        internal virtual bool RequiresAtomicStartTransition => true;
-
         /// <summary>
         /// Calls QueueTask() after performing any needed firing of events
         /// </summary>

src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/ThreadPoolTaskScheduler.cs

@@ -114,11 +114,5 @@ internal override void NotifyWorkItemProgress()
         {
             ThreadPool.NotifyWorkItemProgress();
         }
-
-        /// <summary>
-        /// This is the only scheduler that returns false for this property, indicating that the task entry codepath is unsafe (CAS free)
-        /// since we know that the underlying scheduler already takes care of atomic transitions from queued to non-queued.
-        /// </summary>
-        internal override bool RequiresAtomicStartTransition => false;
     }
 }

src/libraries/System.Private.CoreLib/src/System/Threading/Timer.cs

@@ -973,23 +973,5 @@ public ValueTask DisposeAsync()
         }
 
         private string DisplayString => _timer._timer.DisplayString;
-
-        /// <summary>Gets a list of all timers for debugging purposes.</summary>
-        private static IEnumerable<TimerQueueTimer> AllTimers // intended to be used by devs from debugger
-        {
-            get
-            {
-                var timers = new List<TimerQueueTimer>();
-
-                foreach (TimerQueue queue in TimerQueue.Instances)
-                {
-                    timers.AddRange(queue.GetTimersForDebugger());
-                }
-
-                timers.Sort((t1, t2) => t1._dueTime.CompareTo(t2._dueTime));
-
-                return timers;
-            }
-        }
     }
 }