Avoid N+1 issue when rendering import count

Calling `patient` makes a query to the database whereas we just need the
ID of the patient.

Author: thomasleese

app/components/app_imports_navigation_component.rb

@@ -43,7 +43,7 @@ def issues_text
 
     unique_import_issues =
       (vaccination_records_with_issues + patients_with_issues).uniq do |record|
-        record.is_a?(VaccinationRecord) ? record.patient : record
+        record.is_a?(VaccinationRecord) ? record.patient_id : record.id
       end
 
     count = unique_import_issues.count