Fix issue where plugin settings had higher precedence than manageiq

One of the side effects of this is that in production deployments with
overrides, the overrides were being clobbered by the plugins.

https://bugzilla.redhat.com/show_bug.cgi?id=1517938

lib/vmdb/settings.rb

@@ -111,30 +111,28 @@ def self.build_without_local(resource)
     private_class_method :build_without_local
 
     def self.template_roots
-      Vmdb::Plugins.instance.vmdb_plugins.each_with_object([Rails.root.join('config')]) do |plugin, roots|
-        roots << plugin.root.join('config')
-      end
+      Vmdb::Plugins.instance.vmdb_plugins.collect { |p| p.root.join('config') } << Rails.root.join('config')
     end
     private_class_method :template_roots
 
     def self.template_sources
-      template_roots.each_with_object([]) do |root, sources|
-        sources.push(
+      template_roots.flat_map do |root|
+        [
           root.join("settings.yml").to_s,
           root.join("settings/#{Rails.env}.yml").to_s,
           root.join("environments/#{Rails.env}.yml").to_s
-        )
+        ]
       end
     end
     private_class_method :template_sources
 
     def self.local_sources
-      template_roots.each_with_object([]) do |root, sources|
-        sources.push(
+      template_roots.flat_map do |root|
+        [
           root.join("settings.local.yml").to_s,
           root.join("settings/#{Rails.env}.local.yml").to_s,
           root.join("environments/#{Rails.env}.local.yml").to_s
-        )
+        ]
       end
     end
     private_class_method :local_sources