Remove unused imports in DatabaseService to improve code cleanliness

Author: Sandro642

src/main/java/io/nodelink/server/app/infra/DatabaseService.java

@@ -1,8 +1,5 @@
 package io.nodelink.server.app.infra;
 
-import com.fasterxml.jackson.databind.JsonNode;
-import com.fasterxml.jackson.databind.ObjectMapper;
-
 import java.sql.*;
 
 public class DatabaseService {