Suicide Attack Kills 2 in Israel; 16 Hurt JERUSALEM - A Palestinian teenager blew herself up at a busy Jerusalem bus station Wednesday, killing two Israeli policemen who stopped her for a security check and wounding 16 bystanders in an attack that evaded Israel's clampdown on the West Bank for the Jewish holidays.    Prime Minister Ariel Sharon, meanwhile, dropped a plan to evacuate 21 Jewish settlements in the Gaza Strip simultaneously at the beginning of next year, reverting to an earlier formula - a staged pullout in the summer of 2005...