Delete authenticated users when running unit test

[g-viet]

Note:

• QUOTA EXCEED of deleting authenticated Users has been limited: 10 requests per second.

  
  const clearAuthUsers: any = async (auth: auth.Auth, remainingUsers?: auth.UserRecord[]) => {
  return await auth.listUsers().then(userList => {
      const shouldDeleteUsers = remainingUsers ? remainingUsers.slice(0, 9) : userList.users.slice(0, 9);
      remainingUsers = remainingUsers ? remainingUsers.slice(10, -1) : userList.users.slice(10, -1);
  
      const deleteUserTasks = shouldDeleteUsers.map(user => auth.deleteUser(user.uid));
      return Promise.all(deleteUserTasks)
          .then(() => {
              if (remainingUsers.length === 0) return null;
              return setTimeout(() => {
                  return clearAuthUsers(auth, remainingUsers);
              }, 1000);
          });
  });
  };