generic softwares should be pulled from respective vendors not through elastic

```
favorite-python:
build: python-favorite/.
image: docker.elastic.co/demos/workshop/observability/elastiflix-python-favorite:${ELASTIC_VERSION}-${BUILD_NUMBER}

favorite-go:
build: go-favorite/.
image: docker.elastic.co/demos/workshop/observability/elastiflix-go-favorite:${ELASTIC_VERSION}-${BUILD_NUMBER}

favorite-java:
build: java-favorite/.
image: docker.elastic.co/demos/workshop/observability/elastiflix-java-favorite:${ELASTIC_VERSION}-${BUILD_NUMBER}

node-server:
build: node-server/.
image: docker.elastic.co/demos/workshop/observability/elastiflix-node-server:${ELASTIC_VERSION}-${BUILD_NUMBER}
redis:
build: redis/.
image: docker.elastic.co/demos/workshop/observability/elastiflix-redis:${ELASTIC_VERSION}-${BUILD_NUMBER}

```

e.g redis can be pulled from docker hub with image value `redis:latest `not from elastic...