Don't display ocr_language in manifest. (pulibrary#550)

Closes pulibrary#549.

app/schemas/plum_schema.rb

@@ -290,7 +290,7 @@ class PlumSchema < ActiveTriples::Schema
   # Ignore things like admin data (workflow note), title, description, etc, as
   # those have custom display logic.
   def self.display_fields
-    ScannedResource.properties.values.map(&:term) - [:description, :state, :rights_statement, :holding_location, :title, :depositor, :source_metadata_identifier, :source_metadata, :date_modified, :date_uploaded, :workflow_note, :nav_date, :pdf_type] - IIIFBookSchema.properties.map(&:name)
+    ScannedResource.properties.values.map(&:term) - [:description, :state, :rights_statement, :holding_location, :title, :depositor, :source_metadata_identifier, :source_metadata, :date_modified, :date_uploaded, :workflow_note, :nav_date, :pdf_type, :ocr_language] - IIIFBookSchema.properties.map(&:name)
   end
 end
 # rubocop:enable Metrics/ClassLength

spec/services/polymorphic_manifest_builder_spec.rb

@@ -286,6 +286,10 @@ def build_file_set(id)
       it "is empty with no metadata" do
         expect(result.metadata).to be_empty
       end
+      it "doesn't render ocr_language" do
+        record.ocr_language = ["test"]
+        expect(result.metadata.first).to be_nil
+      end
       it "has a date created" do
         record.date_created = ["1981-01-31"]
         expect(result.metadata).not_to be_empty