Fix port mapping logic
Prevent crash if neither ELASTICSEARCH_PORT
nor ELASTICSEARCH_PORT_9200
env vars are set.
Previous logic was unnecessarily complex. Docker compose will happily parse :9200
port mapping and use an ephemeral port.
The env vars for configuring port mappings is now in the format {SERVICE}_PORT_{INTERNAL_PORT_NUMBER}
e.g. MYSQL_PORT_3306
.
Bug: T387729