Add DJANGO_SUPERUSER_SSO_EMAIL_USER_ID to sample env file
Add DJANGO_SUPERUSER_SSO_EMAIL_USER_ID to sample env file

This adds `DJANGO_SUPERUSER_SSO_EMAIL_USER_ID` to the sample env file following https://github.com/uktrade/data-hub-api/pull/2784.
uktrade/data-hub-frontend,uktrade/data-hub-frontend,uktrade/data-hub-fe-beta2,uktrade/data-hub-fe-beta2,uktrade/data-hub-frontend