add fixme comment to replace duplicate nodename cache

that function also caches the value, and it recently was changed to
be importable, so we can just import and drop this once a new enough
pve-common is available.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

PVE/QemuServer.pm

@@ -121,8 +121,7 @@ PVE::JSONSchema::register_standard_option('pve-qemu-machine', {
 	optional => 1,
 });
 
-#no warnings 'redefine';
-
+# FIXME: remove in favor of just using the INotify one, it's cached there exactly the same way
 my $nodename_cache;
 sub nodename {
     $nodename_cache //= PVE::INotify::nodename();