chore: use a local image of unleash enterprise for testing FE (#9509)

This removes the need of running a heroku instance with enterprise to
run frontend tests. We can also get rid of vercel deployments of the
frontend for PRs (ofc we'd be loosing the preview if we do this)

It relies on the free enterprise docker image to spin up a clean Unleash
instance on each frontend spec test.

It also seems to speed up tests, I guess because we don't have to wait
for vercel deployment queue:

![image](https://github.com/user-attachments/assets/60a2aef1-9a5a-442d-b241-8c5c145c679e)


Compared with other recent PRs:

![image](https://github.com/user-attachments/assets/9a7498aa-26e6-48a4-aba0-c67e5380ced4)

Unrelated to this PR but something is making the features spec tests
very slow since Cypress upgrade:
https://github.com/Unleash/unleash/actions/runs/13784760762/job/38550079932#step:4:138

Author: gastonfournier

.github/docker-compose.test.yml

@@ -0,0 +1,55 @@
+# This docker compose setup configures:
+# - the Unleash enterprise server instance + the necessary backing Postgres database
+#
+# To learn more about all the parts of Unleash, visit
+# https://docs.getunleash.io
+#
+# NOTE: please do not use this configuration for production setups.
+# Unleash does not take responsibility for any data leaks or other
+# problems that may arise as a result.
+#
+# This is intended to be used for demo, development, and learning
+# purposes only.
+
+services:
+  # The Unleash server contains the Unleash configuration and
+  # communicates with server-side SDKs and the Unleash Proxy
+  unleash:
+    image: 726824350591.dkr.ecr.eu-central-1.amazonaws.com/unleash-enterprise:latest
+    pull_policy: "always"
+    ports:
+      - "4242:4242"
+    environment:
+      DATABASE_URL: "postgres://postgres:unleash@db/unleash"
+      DATABASE_SSL: "false"
+      UNLEASH_LICENSE: "${FRONTEND_TEST_LICENSE}"
+    depends_on:
+      db:
+        condition: service_healthy
+    healthcheck:
+      test: wget --no-verbose --tries=1 --spider http://localhost:4242/health || exit 1
+      interval: 1s
+      timeout: 1m
+      retries: 5
+      start_period: 15s
+  db:
+    expose:
+      - "5432"
+    image: postgres:16
+    environment:
+      POSTGRES_DB: "unleash"
+      # trust incoming connections blindly (DON'T DO THIS IN PRODUCTION!)
+      POSTGRES_HOST_AUTH_METHOD: "trust"
+    healthcheck:
+      test:
+        [
+          "CMD",
+          "pg_isready",
+          "--username=postgres",
+          "--host=127.0.0.1",
+          "--port=5432",
+        ]
+      interval: 2s
+      timeout: 1m
+      retries: 5
+      start_period: 10s

.github/workflows/e2e.frontend.yaml

@@ -1,8 +1,10 @@
 name: e2e:frontend
-on: [deployment_status]
+on:
+  pull_request:
+    # paths:
+    #   - 'frontend/**'
 jobs:
   e2e:
-    if: github.event_name == 'deployment_status' && github.event.deployment_status.state == 'success' && contains(github.event.deployment_status.target_url, 'unleash-monorepo-frontend')
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -19,11 +21,17 @@ jobs:
           echo "$GITHUB_CONTEXT"
       - name: Checkout
         uses: actions/checkout@v4
+      - name: Start Unleash test instance
+        run: |
+          curl https://app.unleash-hosted.com/docker-login/token/${{ secrets.ECR_ENTERPRISE_TOKEN }} | docker login --username AWS --password-stdin 726824350591.dkr.ecr.eu-central-1.amazonaws.com
+          docker compose -f .github/docker-compose.test.yml up -d --wait -t 90
+        env:
+          FRONTEND_TEST_LICENSE: ${{ secrets.FRONTEND_TEST_LICENSE }}
       - name: Run Cypress
         uses: cypress-io/github-action@v6
         with:
           working-directory: frontend
           env: AUTH_USER=admin,AUTH_PASSWORD=unleash4all
-          config: baseUrl=${{ github.event.deployment_status.target_url }}
+          config: baseUrl=http://localhost:4242
           spec: cypress/integration/${{ matrix.test }}
           install-command: yarn --immutable