fix: remove Mercure server

compose.override.yaml

@@ -12,7 +12,6 @@ services:
       #  from the bind-mount for better performance by enabling the next line:
       #- /app/vendor
     environment:
-      MERCURE_EXTRA_DIRECTIVES: demo
       # See https://xdebug.org/docs/all_settings#mode
       XDEBUG_MODE: "${XDEBUG_MODE:-off}"
     extra_hosts:
@@ -20,9 +19,6 @@ services:
       - host.docker.internal:host-gateway
     tty: true
 
-###> symfony/mercure-bundle ###
-###< symfony/mercure-bundle ###
-
 ###> doctrine/doctrine-bundle ###
   database:
     ports: