initialize to max value so that there is no conflict when finding oldest cache.

src/EditorFeatures/Core/Implementation/Workspaces/ProjectCacheService.SimpleMRUCache.cs

@@ -37,7 +37,7 @@ public bool Empty
             public void Touch(object instance)
             {
                 var oldIndex = -1;
-                var oldTime = DateTime.UtcNow;
+                var oldTime = DateTime.MaxValue;
 
                 for (var i = 0; i < _nodes.Length; i++)
                 {