fix(indexer): Fix concurrency issues in ReindexThread (#30083) (#30084)

Fixes concurrency issues and prevents race conditions that cause the
indexer from hanging or shutting down immediately after startup.

This PR resolves #30083 (Startup timeouts due to indexer concurrency
issues).

dotCMS/src/main/java/com/dotmarketing/common/reindex/ReindexThread.java

@@ -327,8 +327,6 @@ private static void unpauseImpl() {
             OSGISystem.getInstance().initializeFramework();
             Logger.infoEvery(ReindexThread.class, "--- ReindexThread Running", 60000);
             cache.get().remove(REINDEX_THREAD_PAUSED);
-            final Thread thread = new Thread(getInstance().ReindexThreadRunnable,
-                    "ReindexThreadRunnable");
 
             final DotSubmitter submitter = DotConcurrentFactory.getInstance()
                     .getSubmitter("ReindexThreadSubmitter",
@@ -340,8 +338,8 @@ private static void unpauseImpl() {
                                             new ThreadPoolExecutor.DiscardOldestPolicy())
                                     .build()
                     );
-            submitter.submit(thread);
             getInstance().state(ThreadState.RUNNING);
+            submitter.submit(getInstance().ReindexThreadRunnable);
         }
 
     }