Add test for executor

src/Managing.Application/Users/UserService.cs

@@ -296,8 +296,7 @@ public class UserService : IUserService
 
     public async Task<User> GetUserByIdAsync(int userId)
     {
-        var allUsers = await _userRepository.GetAllUsersAsync();
-        var user = allUsers.FirstOrDefault(u => u.Id == userId);
+        var user = await _userRepository.GetUserByIdAsync(userId);
 
         if (user == null)
         {