Viewers who tune in to “American Idol” on March 11 are no doubt eager to see the contenders and celebrity judges Katy Perry, Lionel Richie, and Luke Bryan. They will also see prominent ad pitches from Macy’s and Zyrtec. The retailer and the Johnson & Johnson allergy medication will be woven into the content of the musical-competition program, according to two people familiar with the matter, playing roles similar to the ones filled by big advertisers like Coke,  Ford Motor and AT&T when “Idol” enjoyed a much-ballyhooed and top-rated run on Fox between 2002 and 2016.