Add playbooks directory and a common playbook

For now, this is a basic one intended just to run the common role on
every host.
Status Job ID Name Coverage
  Galaxy
passed #4819
preprod
galaxy:install

00:00:28

 
  Test Syntax
failed #4820
preprod
syntax:check

00:00:02

 
Name Stage Failure
failed
syntax:check Test Syntax
Clean repository
Checking out b360aa34 as ssh_management...
Skipping Git submodules setup
Downloading artifacts for galaxy:install (4819)...
Runtime platform arch=amd64 os=linux pid=15675 revision=692ae235 version=11.9.0
Downloading artifacts from coordinator... ok id=4819 responseStatus=200 OK token=uiPFrHxF
$ ansible-playbook --syntax-check site.yml
ERROR! The vault password file /home/gitlab-runner/builds/5e18bbcf/0/lqdn-interne/piops/.password was not found
ERROR: Job failed: exit status 1