[Etherpad] Disable backups of pad.picasoft.net

Revert this commit to enable backups again.

Backups were run every six hours, but due to the huge increase in the 
size of our DB (Docker volume 'etherpad-db' takes 47 GB at this time), 
backups take almost 3h30 to complete, slowing down the entire instance 
during that period.

pica-db-backup/config/backup_config.json

@@ -10,18 +10,6 @@
     "Cron": "0 * * * *",
     "Init-Backup": "1"
   },
-  "etherpad": {
-    "Host": "etherpad-db",
-    "Port": "3306",
-    "User": "ETHERPAD_DB_USER",
-    "Password": "ETHERPAD_DB_PASSWORD",
-    "Database": "--all-databases",
-    "Type": "mysql",
-    "Folder": "etherpad",
-    "Cron": "0 */6 * * *",
-    "Options": "--single-transaction",
-    "Init-Backup": "1"
-  },
   "wekan": {
     "Host": "wekan-db",
     "Port": "27017",