What is the ruling of the Sharia on someone who receives a salary from the state without performing actual work, based on the instructions of his superior who affirmed the full payment of the salary without requiring his attendance?

It is not permissible for a Muslim to take another's money except through lawful means. A contracted employee with their employer for a specific time is not permitted to violate that, even if their manager exempts them, unless the manager is authorized by the employer to grant them that time. In that case, the salary would be a gift.