use the parallelism level for ctags watcher as well for a good measure

Author: vladak

opengrok-indexer/src/main/java/org/opengrok/indexer/index/IndexerParallelizer.java

@@ -242,7 +242,7 @@ private void createLazyCtagsPool() {
 
     private void createLazyCtagsWatcherExecutor() {
         lzCtagsWatcherExecutor = LazilyInstantiate.using(() ->
-                new ScheduledThreadPoolExecutor(1,
+                new ScheduledThreadPoolExecutor(indexingParallelism,
                         new OpenGrokThreadFactory("ctags-watcher")));
     }