THIS WEEK TWO PBS PROGRAMS touch on the more stressful aspects of the holiday season. On Thursday (Dec. 17, 8 RM. ET) there is America's at the Mall, a comprehensive history of the big enclosed shopping centers where so many of us flock desperately at this time of year. If the prospect of too boisterous office parties and family get-togethers makes you wince, you may want to check out Tuesday's Nova (Dec. 22, 8 RM. ET), Can You Stop People from Drinking?, a study of efforts to curb chronic drinking, including experiments with aversion therapy as grotesque as anything in A Clockwork Orange.