Change the delay for how often we synchronize solutions

Now that we're doing all the WorkspaceChanged notifications on
background threads, that means the notifications won't be quite as
batched as before; this was causing an increase in synchronizations
that was creating some wasted work.

Author: jasonmalinowski

src/EditorFeatures/Core/Remote/SolutionChecksumUpdater.cs

@@ -59,7 +59,7 @@ public SolutionChecksumUpdater(
         _shutdownToken = shutdownToken;
 
         _synchronizeWorkspaceQueue = new AsyncBatchingWorkQueue(
-            DelayTimeSpan.NearImmediate,
+            DelayTimeSpan.Short,
             SynchronizePrimaryWorkspaceAsync,
             listener,
             shutdownToken);