refactor teacher response rate calculator

app/models/teacher_response_rate_calculator.rb

@@ -4,7 +4,7 @@ class TeacherResponseRateCalculator
   def survey_item_count
     @survey_item_count ||= @subcategory.measures.map do |measure|
       measure.teacher_survey_items.reject do |survey_item|
-        survey_item.survey_item_responses.where(school: @school, academic_year: @academic_year).none?
+        survey_item.survey_item_responses.where(school:, academic_year:).none?
       end.count
     end.sum
   end
@@ -12,15 +12,15 @@ class TeacherResponseRateCalculator
   def response_count
     @response_count ||= @subcategory.measures.map do |measure|
       measure.teacher_survey_items.map do |survey_item|
-        survey_item.survey_item_responses.where(school: @school,
-                                                academic_year: @academic_year).exclude_boston.count
+        survey_item.survey_item_responses.where(school:,
+                                                academic_year:).exclude_boston.count
       end.sum
     end.sum
   end
 
   def total_possible_responses
     @total_possible_responses ||= begin
-      total_responses = Respondent.where(school: @school, academic_year: @academic_year).first
+      total_responses = Respondent.where(school:, academic_year:).first
       return 0 unless total_responses.present?
 
       total_responses.total_teachers