#7256 close channel underlying the queue's filelock

Fixes #7257

logstash-core/src/main/java/org/logstash/FileLockFactory.java

@@ -114,6 +114,7 @@ public class FileLockFactory {
         String lockPath = LOCK_MAP.remove(lock);
         if (lockPath == null) { throw new LockException("Cannot release unobtained lock"); }
         lock.release();
+        lock.channel().close();
         Boolean removed = LOCK_HELD.remove(lockPath);
         if (removed == false) { throw new LockException("Lock path was not marked as held: " + lockPath); }
     }