Revert "[Etherpad] Disable rotation of pad.picasoft.net backups"

This reverts commit 02e51284.

pica-db-backup-rotation/config/backup_config.json

@@ -10,6 +10,17 @@
               "Month" : 12
           }
     },
+    "etherpad":
+    {
+      "Folder": "etherpad",
+      "Backup-Rota":
+          {
+              "Hour" : 24,
+              "Day" : 7,
+              "Week" : 4,
+              "Month" : 12
+          }
+    },
     "wekan":
       {
         "Folder": "wekan",