Optimized ArbitraryDataFileRequestThread - only start a database transaction when there's something to process.

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileRequestThread.java

@@ -42,7 +42,6 @@ public class ArbitraryDataFileRequestThread implements Runnable {
     }
 
     private void processFileHashes(Long now) {
-        try (final Repository repository = RepositoryManager.getRepository()) {
         ArbitraryDataFileManager arbitraryDataFileManager = ArbitraryDataFileManager.getInstance();
 
         ArbitraryTransactionData arbitraryTransactionData = null;
@@ -97,6 +96,7 @@ public class ArbitraryDataFileRequestThread implements Runnable {
         }
 
         // Fetch the transaction data
+        try (final Repository repository = RepositoryManager.getRepository()) {
             arbitraryTransactionData = ArbitraryTransactionUtils.fetchTransactionData(repository, signature);
             if (arbitraryTransactionData == null) {
                 return;