chore: Adopt docker-compose-base.yml extends pattern for MassTransit compose

Aligns with the refactor in main that extracts common service config
into docker-compose-base.yml.

Author: tippmar-nr

tests/Agent/IntegrationTests/ContainerApplications/docker-compose-masstransit.yml

@@ -1,50 +1,21 @@
 # The following must be set either in environment variables or via a .env file in the same folder as this file:
 #
-# AGENT_PATH      host path to the Agent linux home folder - will map to /usr/local/newrelic-dotnet-agent in the container
-# LOG_PATH        host path for Agent logfile output - will map to /app/logs in the container
-# DISTRO_TAG      distro tag for build, not including the architecture suffix
-# TARGET_ARCH     the target architecture for the run -- either amd64 or arm64
-# BUILD_ARCH      the build architecture -- either amd64 or arm64
-# PORT            external port for the smoketest API
+# See docker-compose-base.yml for common required variables.
 # CONTAINER_NAME  The name for the container
-# PLATFORM        The platform that the service runs on -- linux/amd64 or linux/arm64/v8
-# DOTNET_VERSION  The dotnet version number to use (8.0, etc)
-# TEST_DOCKERFILE The path and dockerfile to use for the service.
-#
 # MASSTRANSIT_KAFKA_TOPIC
 # MASSTRANSIT_RABBITMQ_QUEUE
 #
-# and the usual suspects:
-# NEW_RELIC_LICENSE_KEY
-# NEW_RELIC_HOST
-# NEW_RELIC_APP_NAME
-#
-#
 # To build and run, execute `docker compose -f <path to docker-compose.yml> up`
 # Alternatively, set COMPOSE_FILE environment variable to the path and omit the -f parameter
 
 services:
     LinuxSmokeTestApp:
+        extends:
+            file: docker-compose-base.yml
+            service: base-app
         container_name: ${CONTAINER_NAME}
         image: ${CONTAINER_NAME}
         platform: ${PLATFORM}
-        build:
-            context: .
-            dockerfile: ${TEST_DOCKERFILE}
-            args:
-                DISTRO_TAG: ${DISTRO_TAG}
-                TARGET_ARCH: ${TARGET_ARCH}
-                BUILD_ARCH: ${BUILD_ARCH}
-                NEW_RELIC_LICENSE_KEY: ${NEW_RELIC_LICENSE_KEY}
-                NEW_RELIC_APP_NAME: ${NEW_RELIC_APP_NAME}
-                NEW_RELIC_HOST: ${NEW_RELIC_HOST}
-                DOTNET_VERSION: ${DOTNET_VERSION}
-                APP_DOTNET_VERSION: ${APP_DOTNET_VERSION}
-        ports:
-          - "${PORT}:80"
-        volumes:
-          - ${AGENT_PATH}:/usr/local/newrelic-dotnet-agent
-          - ${LOG_PATH}:/app/logs
         depends_on:
             - kafka-broker
             - rabbitmq
@@ -79,7 +50,6 @@ services:
           RABBITMQ_DEFAULT_USER: guest
           RABBITMQ_DEFAULT_PASS: guest
 
-
 networks:
     default:
         driver: bridge