Change default behavior of ENABLE DB MIGRATION (#9077)

See:
https://github.com/twentyhq/twenty/issues/9031#issuecomment-2542015975

I think it would be easier if the default behavior for the container was
to run the migration, and setting the environment variable would be used
to disable it (e.g. on the worker).

Long-term goal is for the default setup to work out of the box with ~2
env variables only (database url, redis url)

I don't think there's a big risk if people forget to turn it off on the
worker?

packages/twenty-docker/twenty/entrypoint.sh

@@ -2,7 +2,7 @@
 set -e
 
 # Check if the initialization has already been done and that we enabled automatic migration
-if [ "${ENABLE_DB_MIGRATIONS}" = "true" ] && [ ! -f /app/docker-data/db_status ]; then
+if [ "${DISABLE_DB_MIGRATIONS}" != "true" ] && [ ! -f /app/docker-data/db_status ]; then
     echo "Running database setup and migrations..."
 
     # Creating the database if it doesn't exist