KABUL — NATO officials in Afghanistan this week stopped transferring detainees to Afghan custody in several provinces in response to a United Nations probe that found evidence of systematic torture at some detention centers, the military command said Tuesday night. The move represents a serious setback for the United States and its allies in Afghanistan at a time when the international community is beginning to pull out troops and move more responsibility for security to the Afghans. The findings of a report on detainee abuse, which the U.N.