Is it obligatory to change the name "Ayyash", which was given with the intention of "long life", and which contradicts the belief that lifespans are in God's hands?

There is no need to change your name, for this name existed among the righteous predecessors, and it is a permissible form of optimism in Islamic law. It does not contradict the fact that all lives and affairs are in the hand of Allah. The Prophet, peace and blessings be upon him, used to like good omens. This is indicated by the hadith in Al-Muwatta where the Prophet, peace and blessings be upon him, commanded a person named "Ya'ish" (meaning 'he lives') to milk a camel, while he ordered "Murrah" (meaning 'bitterness') and "Harb" (meaning 'war') to sit down, because the Prophet, peace and blessings be upon him, informed that the worst names are Harb and Murrah.