optimized get_dashboard_dates to avoid seq scan
optimized get_dashboard_dates to avoid seq scan

AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,berkmancenter/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,berkmancenter/mediacloud,berkmancenter/mediacloud,berkmancenter/mediacloud,berkmancenter/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud