[docker-compose] Update deprecated localstack config

Summary:
Details in [[ https://linear.app/comm/issue/ENG-5677/commtest-ci-is-broken | ENG-5677 ]].
Some of the config environment variables for Localstack are deprecated.
I've updated them according to [[ https://docs.localstack.cloud/references/configuration/ | the docs ]].

Depends on D9740

Test Plan:
- Run localstack locally and use it (e.g. integration tests)
- Stop and restart localstack container, check if the data is still there (DDB and S3 items)
- Run this on CI

Reviewers: kamil, michal, atul

Reviewed By: atul

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9742

services/docker-compose.tests.yml

@@ -75,6 +75,9 @@ services:
       args:
         - generate_keypair=true
 
+  localstack:
+    environment:
+      - PERSISTENCE=0
   rabbitmq:
     healthcheck:
       test: rabbitmq-diagnostics -q ping

services/docker-compose.yml

@@ -92,10 +92,10 @@ services:
       - '4566:4566'
     environment:
       - SERVICES=s3,dynamodb
-      - DATA_DIR=/tmp/localstack
-      - HOSTNAME_EXTERNAL=localstack
+      - LOCALSTACK_HOST=localstack:4566
+      - PERSISTENCE=1
     volumes:
-      - localstack:/tmp/localstack
+      - localstack:/var/lib/localstack
   # RabbitMQ
   rabbitmq:
     # This version matches AWS MQ version (set in Terraform)