Do not include placement::config by default

... because there is no requirement to have this inclusion.

Change-Id: I1b7380dfcd6b009328e334dd4b5701dd529fceee

manifests/db.pp

@@ -70,7 +70,6 @@ class placement::db (
 ) {
 
   include placement::deps
-  include placement::config
 
   oslo::db { 'placement_config':
     config_group       => 'placement_database',

releasenotes/notes/placement-db-includes-placmenet-config-8015c11cda289a3b.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Now the ``placmenet::db`` class doesn't include the ``placement::config``
+    class automatically. Include the ``placement::config`` explicitly in
+    manifests if the class is required.

spec/classes/placement_db_spec.rb

@@ -5,7 +5,6 @@ describe 'placement::db' do
     context 'with default parameters' do
       it {
         should contain_class('placement::deps')
-        should contain_class('placement::config')
       }
 
       it { should contain_oslo__db('placement_config').with(
@@ -45,7 +44,6 @@ describe 'placement::db' do
 
       it {
         should contain_class('placement::deps')
-        should contain_class('placement::config')
       }
 
       it { should contain_oslo__db('placement_config').with(