remove useless DATAGOUV_TMP_DIR env

app/jobs/cron/datagouv/export_and_publish_demarches_publiques_job.rb

@@ -3,7 +3,7 @@ class Cron::Datagouv::ExportAndPublishDemarchesPubliquesJob < Cron::CronJob
 
   def perform(*args)
     gzip_filepath = [
-      ENV.fetch('DATAGOUV_TMP_DIR', 'tmp'), '/',
+      'tmp/',
       Time.zone.now.to_formatted_s(:number),
       '-demarches.json.gz'
     ].join

config/env.example.optional

@@ -142,5 +142,3 @@ VITE_LEGACY=""
 NEW_MAX_DUREE_CONSERVATION=12
 #
 OPENDATA_ENABLED="enabled"
-# Directory which temporarily holds demarches.json.gz during generation before publishing to datagouv
-DATAGOUV_TMP_DIR="/tmp"