Fix unit tests incompatible with puppetlab-stdlib 8.0.0

Since puppetlabs-stdlib 8.0.0, ensure_packages automatically translates
'ensure => present'  to 'ensure => installed' and that translation
breaks existing assertions in unit tests.

Change-Id: Id592ca8181caaaae448e2c965a5d61b46c1b9748

spec/classes/gnocchi_storage_ceph_spec.rb

@@ -24,7 +24,7 @@ describe 'gnocchi::storage::ceph' do
       end
 
       it { is_expected.to contain_package('python-rados').with(
-        :ensure => 'present',
+        :ensure => 'installed',
         :name   => 'python3-rados',
         :tag    => ['openstack', 'gnocchi-package'],
       )}