NEW DELHI — People weren’t frying eggs on the sidewalks in Phalodi during India ’s hottest day ever — in fact, it was so hot that many did not venture out at all. Heat is a familiar part of life in Phalodi, in the deserts of Rajasthan, so residents were following a familiar drill even before temperatures soared to 123.8 degrees Fahrenheit on Thursday: When the heat comes, stay indoors, chug buttermilk and, if you must go out, cover your head and pray for shade. It is a drill that may prove ever more necessary if temperatures continue to rise.