Manage Postgresql data dir with Puppet
Default data directory (/var/lib/postgresql/...) is created during
installation of debian package. In case we want to use another data directory,
like it is the case for maps servers, this directory is not created and need
to be managed by Puppet.
Minor refactoring of existing tests was done to ensure all tests are green.
Bug: T138092
Change-Id: Iec59cf0290a5ea34cdab26d3604b32a9edde4967