By Christine Chen and Cordelia HsuSYDNEY, April 3 (Reuters) - Every Easter, Sydney retiree Elsa Ulcak is one of the millions of Australians that hit the road to travel during the four-day-long weekend. But this year, she has cancelled her trip with her husband because she could not justify how much petrol her getaway would use."We usually go to the countryside, but because of the petrol situation, we decided to stay at home this year," said Ulcak, 67. A long trip would be costly and also consum...