Avoid unneeded memory consumption for Zendesk import.

lib/import/zendesk/requester.rb

@@ -32,6 +32,11 @@ module Import
           # when hitting the rate limit, sleep automatically,
           # then retry the request.
           config.retry = true
+
+          # disable cache to avoid unneeded memory consumption
+          # since we are using each object only once
+          # Inspired by: https://medium.com/swiftype-engineering/using-jmat-to-find-analyze-memory-in-jruby-1c4196c1ec72
+          config.cache = false
         end
       end
     end