config: drop 'maxfiles' parameter

The 'maxfiles' parameter has been deprecated since the addition of
'prune-backups' in the Proxmox VE 7 beta.

The setting was auto-converted when reading the storage
configuration.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Link: https://lore.proxmox.com/20250718125408.133376-2-f.ebner@proxmox.com

src/PVE/Storage/NFSPlugin.pm

@@ -93,7 +93,6 @@ sub options {
         export => { fixed => 1 },
         nodes => { optional => 1 },
         disable => { optional => 1 },
-        maxfiles => { optional => 1 },
         'prune-backups' => { optional => 1 },
         'max-protected-backups' => { optional => 1 },
         options => { optional => 1 },