chore: update variable name as per review comment

Author: salman2013

docker-compose-watchers.yml

@@ -5,7 +5,7 @@ services:
     command: bash -c 'cd /edx/app/edxapp/edx-platform && source ../edxapp_env && while true; do paver watch_assets --w=$$ASSET_WATCHER_TIMEOUT; sleep 2; done'
     container_name: "edx.${COMPOSE_PROJECT_NAME:-devstack}.lms_watcher"
     environment:
-      SERVER_HOSTNAME: edx.devstack.lms_watcher
+      FRONTEND_TEST_SERVER_HOSTNAME: edx.devstack.lms_watcher
       ASSET_WATCHER_TIMEOUT: 12
     image: openedx/lms-dev:${OPENEDX_RELEASE:-latest}
     volumes:
@@ -23,7 +23,7 @@ services:
     command: bash -c 'cd /edx/app/edxapp/edx-platform && source ../edxapp_env && while true; do paver watch_assets --w=$$ASSET_WATCHER_TIMEOUT; sleep 2; done'
     container_name: "edx.${COMPOSE_PROJECT_NAME:-devstack}.cms_watcher"
     environment:
-      SERVER_HOSTNAME: edx.devstack.cms_watcher
+      FRONTEND_TEST_SERVER_HOSTNAME: edx.devstack.cms_watcher
       ASSET_WATCHER_TIMEOUT: 12
     image: openedx/lms-dev:${OPENEDX_RELEASE:-latest}
     volumes:

docker-compose.yml

@@ -422,7 +422,7 @@ services:
     stdin_open: true
     tty: true
     environment:
-      SERVER_HOSTNAME: edx.devstack.lms
+      FRONTEND_TEST_SERVER_HOSTNAME: edx.devstack.lms
       SERVER_LMS_PORT: 18003
       SERVER_CMS_PORT: 18031
       EDXAPP_TEST_MONGO_HOST: edx.devstack.mongo
@@ -599,7 +599,7 @@ services:
     stdin_open: true
     tty: true
     environment:
-      SERVER_HOSTNAME: edx.devstack.cms
+      FRONTEND_TEST_SERVER_HOSTNAME: edx.devstack.cms
       SERVER_LMS_PORT: 18103
       SERVER_CMS_PORT: 18131
       EDXAPP_TEST_MONGO_HOST: edx.devstack.mongo