Export POSTGRES variables instead of running from within container

docker-compose.yml

@@ -13,10 +13,9 @@ services:
       - CLOUDSDK_CONFIG=/tmp/.config/gcloud
       - CLOUDSDK_CORE_PROJECT
       - POSTGRES_HOST
-      # ensure that the project can access the credentials bucket
-      - AWS_SECRET_ACCESS_KEY
-      - AWS_ACCESS_KEY_ID
+      - POSTGRES_DB
+      - POSTGRES_USER
+      - POSTGRES_PASS
       # variables required for backfill.sh
-      - PROJECT=${CLOUDSDK_CORE_PROJECT}
       - START_DS
       - END_DS