PluginVC should schedule to the local queue instead of the external queue.

In TS-867 a patch was introduced to resolve a crash that was appearing w/ TSFetchURL, the patch would schedule events on the same thread if it is a net thread, if not it will only then schedule with the event processor. If you're scheduling on the same thread, wouldn't it be more efficient to place the event directly on the local queue? It turns out that going to the ExternalQueue under low load it would cause the event to become delayed. Patch Attached.

To best see the symptoms see complaints in (TS-912 and TS-1043).

I have verified that this patch fixes the 10ms symptom seen in TS-912 and TS-1043.