(crawler) Roll back switch to virtual thread pool in crawler

This seems to cause a resource leak, it seems the http library uses thread locals?

code/processes/crawling-process/src/main/java/nu/marginalia/crawl/CrawlerMain.java

@@ -94,7 +94,7 @@ public class CrawlerMain {
                 1);
 
         fetcher = new HttpFetcherImpl(userAgent.uaString(),
-                new Dispatcher(Executors.newVirtualThreadPerTaskExecutor()),
+                new Dispatcher(),
                 new ConnectionPool(5, 10, TimeUnit.SECONDS)
         );
     }