Heineken USA and Heineken International, subsidiaries of the Dutch brewing giant, confirmed today that they have ended their US and corporate relationship with Lowe Worldwide, their advertising agency for the past four years.   In a statement, Heineken confirmed it had not entered into any agreement with any other agency at this time but said it was reviewing a number of options. It expects to make a decision within the next 30 days. Once an agreement is reached, a formal announcement will be made, the company said.