network: do not enter initialized state when the interface is being processed by udevd

Fixes #30056.

src/network/networkd-link.c

@@ -1651,6 +1651,14 @@ static int link_check_initialized(Link *link) {
                 return 0;
         }
 
+        r = device_is_processing(device);
+        if (r < 0)
+                return log_link_warning_errno(link, r, "Failed to determine whether the device is being processed: %m");
+        if (r > 0) {
+                log_link_debug(link, "Interface is being processed by udevd, pending initialization.");
+                return 0;
+        }
+
         return link_initialized(link, device);
 }