Apply suggestions from code review

Co-authored-by: Santiago Bartesaghi <[email protected]>

Author: gonzaM

app/services/builders/chartkick/repository_distribution_data.rb

@@ -44,7 +44,7 @@ def total_value
       end
 
       def total_records
-        @total_records ||= retrieve_records.count
+        @total_records ||= retrieve_records.size
       end
 
       def success_rate

app/services/builders/chartkick/repository_distribution_data_metrics/review_coverage.rb

@@ -24,10 +24,10 @@ def value_for_average(entity)
         end
 
         def zero_coverage_percentage(records)
-          return 0 if records.empty?
+          total_count = records.count
+          return 0 if total_count.zero?
 
           zero_coverage_count = records.with_zero_coverage.count
-          total_count = records.count
 
           ((zero_coverage_count.to_f / total_count) * 100).round
         end