Update .gitlab-ci.yml and ECS task definition to rename backend URL variable to…

Update .gitlab-ci.yml and ECS task definition to rename backend URL variable to app_api_url for consistency in staging deployment configuration.

.gitlab-ci.yml

@@ -90,7 +90,7 @@ deploy_frontend_staging:
     app_env: staging
     app_url: https://spin-wheel-frontend-staging.dev.kacdn.net
     app_image_tag: $CI_REGISTRY_IMAGE/frontend:staging
-    backend_url: https://spin-wheel-backend-staging.dev.kacdn.net
+    app_api_url: https://spin-wheel-backend-staging.dev.kacdn.net
     ecs_task_definition: ${ecs_task_definition_frontend}
     ecs_definition: ${ecs_task_definition_frontend}
     ecs_entrypoint: app:80

config/ecs-task-definition-frontend.json

@@ -21,7 +21,7 @@
         { "name": "NODE_ENV", "value": "production" },
         { "name": "APP_ENV", "value": "{{app_env}}" },
         { "name": "APP_URL", "value": "{{app_url}}" },
-        { "name": "BACKEND_URL", "value": "{{backend_url}}" }
+        { "name": "BACKEND_URL", "value": "{{app_api_url}}" }
       ],
       "logConfiguration": {
         "logDriver": "awslogs",