Run init script at startup when db changed

following from this:
https://stackoverflow.com/questions/56476339/recreation-of-mongodb-container-doesnt-re-run-config-js-file-in-docker-entrypoin
the init script is only run at start. This makes it run for both BEs but
in a later PR we should understand how to rerun it when any seed changes

services/mongodb/docker-compose.yaml

@@ -2,12 +2,14 @@ services:
   mongodb:
     image: mongo:7.0
     volumes:
-      - mongodb_data:/data/db
+      - ${BE_VERSION:-backendnext}_mongodb_data:/data/db
       - ./config/init.js:/docker-entrypoint-initdb.d/init.js
       - ./config/seed:/seed
     environment:
       BE_VERSION: ${BE_VERSION:-backendnext}
 
 volumes:
-  mongodb_data:
+  $BE_VERSION_mongodb_data:
+    driver: local
+  backend_mongodb_data:
     driver: local