The episode has left some senior White House officials questioning the need for a traditional National Security Council and content to leave Secretary of State Marco Rubio, whom Trump on Thursday named as Waltz’s interim replacement, in a caretaker role for quite some time, a decision that will likely diminish an institution that has had a powerful role in shaping the foreign policy of modern presidencies. And it sidelines a key figure in the White House with a long track record of favoring military intervention, officials said.