Remove placeholder logic

Placeholder schemas were added to hold documents that were rendered by
Whitehall and not yet ready to be presented to end users.

This added some complexity to Publishing API and Content Store, as these
routes did not need to be registered with Router.

Therefore removing this logic now all rendering has been migrated out of
Whitehall.

app/queries/get_content_collection.rb

@@ -11,7 +11,7 @@ class GetContentCollection
       :states,
     )
 
-    def initialize(fields:, document_types: [], filters: {}, pagination: Pagination.new, search_query: "", search_in: nil)
+    def initialize(fields:, document_types: @document_types, filters: {}, pagination: Pagination.new, search_query: "", search_in: nil)
       self.document_types = Array(document_types)
       self.fields = (fields || default_fields) + %w[total]
       self.publishing_app = filters[:publishing_app]
@@ -47,17 +47,13 @@ def call
 
     def editions
       scope = Edition.with_document
-      scope = scope.where(document_type: document_types) if document_types.any?
+      scope = scope.where(document_type: @document_types) if @document_types.any?
       scope = scope.where(publishing_app:) if publishing_app
       scope = scope.where("documents.locale": locale) unless locale == "all"
       scope = Link.filter_editions(scope, link_filters) if link_filters.present?
       scope
     end
 
-    def document_types
-      @document_types.flat_map { |d| [d, "placeholder_#{d}"] }
-    end
-
     def validate_fields!
       return unless fields
 

app/queries/get_linkables.rb

@@ -18,17 +18,13 @@ def call
     attr_reader :document_type
 
     def latest_updated_at(document_type)
-      non_placeholder = Edition.where(document_type:)
-        .maximum("updated_at")
-      placeholder = Edition.where(document_type: "placeholder_#{document_type}")
-        .maximum("updated_at")
-      [non_placeholder, placeholder].compact.max
+      Edition.where(document_type:).maximum("updated_at")
     end
 
     def linkables_query(document_type)
       Edition.with_document
         .where(
-          document_type: [document_type, "placeholder_#{document_type}"],
+          document_type:,
           state: %w[published draft],
           "documents.locale": "en",
         )

app/validators/schema_validator.rb

@@ -13,8 +13,6 @@ def initialize(payload:, schema: nil, schema_name: nil, schema_type: :publisher)
   end
 
   def valid?
-    return true if schema_name_exception?
-
     @errors += JSON::Validator.fully_validate(
       schema,
       payload,
@@ -55,10 +53,6 @@ def schema_name
     @schema_name || payload[:schema_name]
   end
 
-  def schema_name_exception?
-    schema_name.to_s.match(/placeholder_/)
-  end
-
   def missing_schema_message
     "Unable to find schema for schema_name #{schema_name}"
   end