LONDON — The British government is being accused of concealing the failure of an unarmed ballistic missile launch ahead of a debate in Parliament over whether to refurbish the country’s aging Trident nuclear launching system. Theresa May told BBC she has full confidence in Britain’s Trident nuclear launching system, but didn’t confirm or deny a report about the alleged failure of a ballistic missile designed to carry nuclear warheads. The newspaper said top government officials decided to keep the failure of a Trident II D5 ballistic missile out of the public eye because of an upcoming debate the next month in Parliament over whether to spend 40 billion pounds to refurbish the aging Trident, the cornerstone of Britain’s nuclear deterrent system.