OP-1538: update dockerfile

Dockerfile

@@ -1,11 +1,14 @@
-FROM postgres:13-alpine
+FROM postgres:13-alpine as base
 
 # Script to detect whether the database has finished initializing
 COPY ["true_isready.sh", "/usr/local/bin/"]
-COPY ["database scripts/00_dump.sql", "database scripts/0[2345]_*.sql", "database scripts/demo_db.sql", "database scripts/json_schema_extension.sql", "/docker-entrypoint-initdb.d/"]
+COPY ["database scripts/00_dump.sql", "database scripts/0[2345]_*.sql", "database scripts/json_schema_extension.sql", "/docker-entrypoint-initdb.d/"]
 
 # Install https://github.com/gavinwahl/postgres-json-schema/
 # extension that allows validation of jsonb fields against jsonschema 
 COPY ["install_postgres_json_schema_extension.sh", "install_postgres_json_schema_extension.sh"]
 RUN chmod u+x install_postgres_json_schema_extension.sh
 RUN ./install_postgres_json_schema_extension.sh
+
+FROM base as demo
+COPY ["database scripts/demo_db.sql", "/docker-entrypoint-initdb.d/"]