By Nandita Bose WASHINGTON (Reuters) – U.S. Vice President Kamala Harris’s National Security Adviser Nancy McEldowney is stepping down from her role and will be succeeded by her deputy Philip Gordon, according to an internal staff memo seen by Reuters. Both McEldowney and Gordon have worked for Harris since she took office and have advised the vice president and President Joe Biden on topics such as Afghanistan, Iran, Ukraine, and cybersecurity. They accompanied Harris on several foreign trips to Central America, Asia and Europe, and have played a key role in shaping her strategy outside the U…