main, vmm: Remove guest_numa_node option from memory zones

The way to describe guest NUMA nodes has been updated through previous
commits, letting the user describe the full NUMA topology through the
--numa parameter (or NumaConfig).

That's why we can remove the deprecated and unused 'guest_numa_node'
option.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vmm/src/memory_manager.rs

@@ -414,7 +414,6 @@ impl MemoryManager {
                 shared: config.shared,
                 hugepages: config.hugepages,
                 host_numa_node: None,
-                guest_numa_node: None,
             }];
 
             (config.size, zones)