Candidates for the job of waking up the country with Kathleen Sullivan five mornings a week--on CBS' still-unnamed morning news program, set to debut Nov. 30--were interviewed and tested this week. The Washington Post reported Thursday that the tryouts were watched by CBS News President Howard Stringer, a producer and a director. The early lead for the job is now considered to be held by Peter Mansbridge, a weekend news anchor for the Canadian Broadcasting Corp. in Toronto. If hired, Mansbridge would become the second Canadian showcased in a national news program. The other is ABC's Peter Jennings.