Apply Style/CollectionMethods rubocop rule

We were already using `map` and `reduce` almost everywhere.

app/helpers/user_segments_helper.rb

@@ -1,6 +1,6 @@
 module UserSegmentsHelper
   def user_segments_options
-    UserSegments::SEGMENTS.collect do |user_segment_name|
+    UserSegments::SEGMENTS.map do |user_segment_name|
       [t("admin.segment_recipient.#{user_segment_name}"), user_segment_name]
     end
   end