[CHORES] fix wait for db script

entrypoint.sh

 #!/bin/sh
 
-if [ "$DATABASE" = "postgres" ]
+if [ -n "$POSTGRES_DB" ]
 then
     echo "Waiting for postgres..."
 
-    while ! nc -z $SQL_HOST $SQL_PORT; do
+    while ! nc -z $POSTGRES_HOST $POSTGRES_PORT; do
       sleep 0.1
     done