Fix new user creation

Summary:
UserAdded was called only when other parameters were provided for a new user beside name and realname.
Which could not happen since 2471fa7d252de904b305dac77171fa300d66c05d and given the order the setData are called in accountinfo.cpp

Alternative to D26977

BUG: 416801
FIXED-IN: 5.18

Test Plan:
Create a new user with a password
in a terminal su new_user

Reviewers: ngraham, davidedmundson, Plasma

Reviewed By: davidedmundson, Plasma

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D26998