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: Ia6f210a661687064b68c864f7064083bc1e71b69

spec/classes/neutron_agents_bgp_dragent_spec.rb

@@ -19,7 +19,7 @@ require 'spec_helper'
 describe 'neutron::agents::bgp_dragent' do
   let :default_params do
     {
-      :package_ensure     => 'present',
+      :package_ensure     => 'installed',
       :enabled            => true,
       :manage_service     => true,
       :bgp_speaker_driver => 'neutron_dynamic_routing.services.bgp.agent.driver.os_ken.driver.OsKenBgpDriver',

spec/classes/neutron_agents_bigswitch_spec.rb

@@ -9,7 +9,7 @@ describe 'neutron::agents::bigswitch' do
     context 'neutron bigswitch base' do
       it 'should have' do
         should contain_package('python3-networking-bigswitch').with(
-          :ensure => 'present',
+          :ensure => 'installed',
           :tag    => ['openstack', 'neutron-package'],
         )
       end

spec/classes/neutron_plugins_ml2_bigswitch_spec.rb

@@ -13,7 +13,7 @@ describe 'neutron::plugins::ml2::bigswitch' do
 
   let :default_params do
     {
-      :package_ensure => 'present'
+      :package_ensure => 'installed'
     }
   end