Set "no_log" for "databases user and setting permissions" tasks

At the moment the "databases user and setting permissions" task for
designate and nova leaks the database_password because of the use
of with_items:

---snip---
TASK [nova : Creating Nova databases user and setting permissions] *********************************************************
ok: [x -> y] => (item={u'database_password': u'password', u'database_name': u'nova', u'database_username': u'nova'})
ok: [x -> y] => (item={u'database_password': u'password', u'database_name': u'nova_cell0', u'database_username': u'nova'})
ok: [x -> y] => (item={u'database_password': u'password', u'database_name': u'nova_api', u'database_username': u'nova_api'})
---snap---

Change-Id: I141e4153223c8772c82a31d81e58057ce266c0b9
Co-authored-by: Bernd Müller <mueller@b1-systems.de>