main: rename landlock_config to landlock_rules

To keep the naming consistent, rename all uses of landlock_config
to landlock_rules.

Signed-off-by: Praveen K Paladugu <prapal@linux.microsoft.com>

src/main.rs

@@ -1066,7 +1066,7 @@ mod unit_tests {
             tpm: None,
             preserved_fds: None,
             landlock_enable: false,
-            landlock_config: None,
+            landlock_rules: None,
         };
 
         assert_eq!(expected_vm_config, result_vm_config);