backups: remove noop backend

the noop backend is migrated into 0 sites config.

when the updater code sees that there is no site to backup, it will
just fail. user has to manually update with skipBackup flag.

dashboard/public/translation/en.json

@@ -194,7 +194,6 @@
         }
     },
     "users": {
-        "newUserAction": "New User",
         "users": {
             "user": "User",
             "groups": "Groups",
@@ -215,7 +214,6 @@
         },
         "groups": {
             "title": "Groups",
-            "newGroupAction": "New Group",
             "name": "Name",
             "users": "Users",
             "externalLdapTooltip": "From external LDAP directory",
@@ -601,7 +599,6 @@
         "configureBackupStorage": {
             "title": "Configure Backup Storage",
             "provider": "Storage provider",
-            "noopNote": "This option breaks the backup and restore functionality of Cloudron and should only be used for testing. Please make sure the server is completely backed up using alternate means.",
             "mountPoint": "Mount point",
             "mountPointDescription": "The mount point has to be set up manually. See <a href=\"{{ providerDocsLink }}\" target=\"_blank\">docs</a>.",
             "localDirectory": "Local backup directory",
@@ -1056,7 +1053,6 @@
     },
     "domains": {
         "title": "Domains & Certs",
-        "addDomain": "Add Domain",
         "domain": "Domain",
         "provider": "Provider",
         "tooltipEdit": "Edit Domain",
@@ -1980,7 +1976,6 @@
     },
     "volumes": {
         "title": "Volumes",
-        "addVolumeAction": "Add Volume",
         "hostPath": "Target",
         "name": "Name",
         "openFileManagerActionTooltip": "File Manager",
@@ -2067,7 +2062,6 @@
         },
         "clients": {
             "title": "OpenID Clients",
-            "newClient": "New Client",
             "empty": "No OpenID Clients"
         }
     },