Fix failing transaction request tests

These tests relied on a publication instance being created, whereas now
the publication method just returns the content item instance.

spec/requests/transactions_spec.rb

@@ -34,7 +34,7 @@
     it "loads the correct details" do
       get "/jobsearch"
 
-      expect(assigns(:publication).title).to eq(@content_item["title"])
+      expect(assigns(:content_item).title).to eq(@content_item["title"])
     end
 
     it "sets correct expiry headers" do
@@ -65,14 +65,14 @@
     it "displays variant specific values where present" do
       get "/foo", params: { variant: "council-tax-bands-2-staging" }
 
-      expect(assigns(:publication).title).to eq(@content_item.dig("details", "variants", 0, "title"))
-      expect(assigns(:publication).transaction_start_link).to eq(@content_item.dig("details", "variants", 0, "transaction_start_link"))
+      expect(assigns(:content_item).title).to eq(@content_item.dig("details", "variants", 0, "title"))
+      expect(assigns(:content_item).transaction_start_link).to eq(@content_item.dig("details", "variants", 0, "transaction_start_link"))
     end
 
     it "displays normal value where variant does not specify value" do
       get "/foo", params: { variant: "council-tax-bands-2-staging" }
 
-      expect(assigns(:publication).more_information).to eq(@content_item.dig("details", "more_information"))
+      expect(assigns(:content_item).more_information).to eq(@content_item.dig("details", "more_information"))
     end
   end
 end