avoid double prefix in thread name

Author: vladak

opengrok-indexer/src/main/java/org/opengrok/indexer/analysis/Ctags.java

@@ -229,7 +229,7 @@ private void run() throws IOException {
         ctagsOut = new BufferedReader(new InputStreamReader(ctagsProcess.getInputStream(),
             StandardCharsets.UTF_8));
 
-        Thread errThread = new OpenGrokThreadFactory("OpenGrok-ctags-err").newThread(() -> {
+        Thread errThread = new OpenGrokThreadFactory("ctags-err").newThread(() -> {
             try (BufferedReader error = new BufferedReader(new InputStreamReader(ctagsProcess.getErrorStream(),
                     StandardCharsets.UTF_8))) {
                 String s;