VSphere CPI creates VM even when folder already exists

Previously if the folder did not exist an attempt would be made to
create it. This could end up in a race condition when max_in_flight is
greater than 1.

This change makes it such that we always attempt to create the folder
and fail gracefully when the folder already exists.

Signed-off-by: Zachary Auerbach <zak@zaksoup.com>