fix(image): re-pin bitnami/discourse -> bitnamilegacy/discourse:3.3.1

Docker Hub emptied the bitnami/discourse namespace (manifest 3.3.1 -> 404, tags:[]); Bitnami moved
archived images to the bitnamilegacy namespace. bitnamilegacy/discourse:3.3.1 is the byte-identical
drop-in (manifest -> 200, same /bitnami/discourse paths + /opt/bitnami scripts). Re-pin both app +
sidekiq services; bump 0.7.0 -> 0.8.0. Found via cc-ci enrollment.

compose.yml

@@ -3,7 +3,7 @@ version: "3.8"
 
 services:
   app:
-    image: bitnami/discourse:3.3.1
+    image: bitnamilegacy/discourse:3.3.1
     networks:
       - proxy
       - internal
@@ -43,7 +43,7 @@ services:
         #- "traefik.http.routers.${STACK_NAME}.middlewares=${STACK_NAME}-redirect"
         #- "traefik.http.middlewares.${STACK_NAME}-redirect.headers.SSLForceHost=true"
         #- "traefik.http.middlewares.${STACK_NAME}-redirect.headers.SSLHost=${DOMAIN}"
-        - "coop-cloud.${STACK_NAME}.version=0.7.0+3.3.1"
+        - "coop-cloud.${STACK_NAME}.version=0.8.0+3.3.1"
     healthcheck:
       test: "ruby -e \"require 'uri'; require 'net/http'; uri = URI('http://localhost:3000/srv/status'); res = Net::HTTP.get_response(uri); if res.is_a?(Net::HTTPSuccess) then exit (0) else exit (1) end\""
       interval: 30s
@@ -84,7 +84,7 @@ services:
       - 'redis_data:/data'
 
   sidekiq:
-    image: bitnami/discourse:3.3.1
+    image: bitnamilegacy/discourse:3.3.1
     networks:
       - proxy
       - internal