BOGOTA, COLOMBIA — Colombian President Gustavo Petro said Friday that he was suspending peace negotiations with National Liberation Army guerrillas after a day of violence between armed groups in the northeast that left at least 30 people dead. The violence took place in the Catatumbo region, on the border with Venezuela, where rival groups have for years been fighting for control of the cocaine trade. The latest fighting pitted rebels from the left-wing National Liberation Army, or ELN — the biggest of the armed groups still active in Colombia — against dissidents from the Marxist Revolutionary Armed Forces of Colombia