Split mailu / roundcube db config

There is no reason to share the flavor since at least the dbname shall be different.

webmails/roundcube/start.py

@@ -10,7 +10,7 @@ log.basicConfig(stream=sys.stderr, level=os.environ.get("LOG_LEVEL", "WARNING"))
 
 os.environ["MAX_FILESIZE"] = str(int(int(os.environ.get("MESSAGE_SIZE_LIMIT"))*0.66/1048576))
 
-db_flavor=os.environ.get("ROUNDCUBE_DB_FLAVOR",os.environ.get("DB_FLAVOR","sqlite"))
+db_flavor=os.environ.get("ROUNDCUBE_DB_FLAVOR","sqlite")
 if db_flavor=="sqlite":
     os.environ["DB_DSNW"]="sqlite:////data/roundcube.db"
 elif db_flavor=="mysql":