Revert "Implemented hacky fix for races in CoyoteRuntime.Dispose"

This reverts commit 151f437e5e.

Source/Core/Runtime/CoyoteRuntime.cs

@@ -76,11 +76,6 @@ namespace Microsoft.Coyote.Runtime
         /// </summary>
         internal readonly Guid Id;
 
-        /// <summary>
-        /// Object that is used to synchronize access to the runtime.
-        /// </summary>
-        private readonly object RuntimeLock;
-
         /// <summary>
         /// The configuration used by the runtime.
         /// </summary>
@@ -297,7 +292,6 @@ namespace Microsoft.Coyote.Runtime
 
             this.Configuration = configuration;
             this.Scheduler = scheduler;
-            this.RuntimeLock = new object();
             this.SyncObject = new object();
             this.OperationIdCounter = 0;
             this.IsRunning = true;
@@ -2412,28 +2406,26 @@ namespace Microsoft.Coyote.Runtime
             if (disposing)
             {
                 RuntimeProvider.Deregister(this.Id);
-                using (SynchronizedSection.Enter(this.RuntimeLock))
+
+                foreach (var op in this.OperationMap.Values)
                 {
-                    foreach (var op in this.OperationMap.Values)
-                    {
-                        op.Dispose();
-                    }
-
-                    this.ThreadPool.Clear();
-                    this.OperationMap.Clear();
-                    this.ControlledThreads.Clear();
-                    this.ControlledTasks.Clear();
-                    this.UncontrolledTasks.Clear();
-                    this.UncontrolledInvocations.Clear();
-
-                    this.DefaultActorExecutionContext.Dispose();
-                    this.ControlledTaskScheduler.Dispose();
-                    this.SyncContext.Dispose();
-                    this.DeadlockMonitor.Dispose();
-                    this.SpecificationMonitors.Clear();
-                    this.TaskLivenessMonitors.Clear();
+                    op.Dispose();
                 }
 
+                this.ThreadPool.Clear();
+                this.OperationMap.Clear();
+                this.ControlledThreads.Clear();
+                this.ControlledTasks.Clear();
+                this.UncontrolledTasks.Clear();
+                this.UncontrolledInvocations.Clear();
+
+                this.DefaultActorExecutionContext.Dispose();
+                this.ControlledTaskScheduler.Dispose();
+                this.SyncContext.Dispose();
+                this.DeadlockMonitor.Dispose();
+                this.SpecificationMonitors.Clear();
+                this.TaskLivenessMonitors.Clear();
+
                 if (this.SchedulingPolicy is SchedulingPolicy.Interleaving)
                 {
                     // Note: this makes it possible to run a Controlled unit test followed by a production