Merge pull request #1928 from ClickHouse/improper-closing

Update StatementImpl.java

Author: Paultagoras

jdbc-v2/src/main/java/com/clickhouse/jdbc/StatementImpl.java

@@ -151,7 +151,6 @@ public int executeUpdate(String sql, QuerySettings settings) throws SQLException
     @Override
     public void close() throws SQLException {
         closed = true;
-        connection.close();
         if (currentResultSet != null) {
             currentResultSet.close();
             currentResultSet = null;