From now, limit_hosts will take precedence over the blacklisted_hostnames.
And therefore Ansible won't be run with two --limit if both limit hosts
and blacklisted hostnames are in use. When we want to run Ansible on
specific hosts, we will ignore the blacklisted nodes and assume we know
what we do. In the case of the scale-down scenario, the unreachable nodes
are ignored.
Note: adding unit tests coverage for both parameters.
Note-bis: unit tests aren't clean backport on train, since Ansible CLI
wasn't exactly the same.
Change-Id: I2e9fc7b9e9005fce7d956f1b936054e540b39849
Closes-Bug: #1857298
(cherry picked from commit 8cd3b14925)
d9433a5af0