Evaluate PASSWORDS_FILE later

Currently seting --configdir on kolla-ansible CLI doesn't set properly the path
for the passwords file.

Change-Id: I38d215b721ec256be6cfdd6313b5ffb90c2a3f4c
Closes-Bug: #1887180
Co-Authored-By: Radosław Piliszek <radoslaw.piliszek@gmail.com>