Hide default batches heading if there are none

This ensures that if no default batches have been selected the heading
isn't displayed as there will be no content below it which looks
strange.

Author: thomasleese

app/controllers/sessions/record_controller.rb

@@ -92,7 +92,7 @@ def set_todays_batches
         end
       end
 
-    @todays_batches = all_batches.compact
+    @todays_batches = all_batches.compact_blank
   end
 
   def set_programme

spec/features/hpv_vaccination_administered_spec.rb

@@ -112,6 +112,7 @@ def and_sync_vaccination_records_to_nhs_on_create_feature_is_enabled
 
   def when_i_go_to_a_patient_that_is_ready_to_vaccinate
     visit session_record_path(@session)
+    expect(page).not_to have_content("Default batches")
     click_link @patient.full_name
   end