WILLIAMSBRIDGE - Family and friends of a Bronx teenager killed during an NYPD narcotics raid held a vigil today to mark the one-month anniversary of his death. Mourners gathered outside the Williamsbridge home of Ramarley Graham, who was fatally shot by a police officer Feb. 2. They lit candles, read poems and recited prayers in his memory. The case is still under investigation, but the sergeant and officer involved have been placed on desk duty. Funeral services held for Ramarley Graham