Revert "platform: workaround for preserving IPv6 address order"

Revert this change again. We are going to backport all the relevant
fixes from nm-1-38 about the address order.

This reverts commit da721a3f320b1e7e4628f7661bf3f78b7f12ed24.

src/libnm-platform/nm-platform.c

@@ -3978,26 +3978,11 @@ nm_platform_ip_address_sync(NMPlatform *self,
     /* @plat_addresses for IPv6 must be sorted in decreasing priority order (highest priority addresses first).
      * IPv4 are probably unsorted or sorted with lowest priority first, but their order doesn't matter because
      * we check the "secondary" flag. */
-    if (IS_IPv4) {
-        plat_addresses = nm_platform_lookup_clone(
-            self,
-            nmp_lookup_init_object(&lookup, NMP_OBJECT_TYPE_IP_ADDRESS(IS_IPv4), ifindex),
-            NULL,
-            NULL);
-    } else {
-        /* HACK: early 1.36 versions had a bug of not actually reordering the IPv6 addresses.
-         * This was fixed by commit cd4601802de5 ('platform: fix address order in
-         * nm_platform_ip_address_sync()').
-         *
-         * However, also in 1.36, the actually implemented order of IPv6 addresses is not
-         * the one we want ([1]). So disable the fix again, to not reorder IPv6 addresses.
-         *
-         * The effect is, that DHCPv6 addresses end up being preferred over SLAAC, because
-         * they get added later during activation. Of course, if any address gets added
-         * even later (like a new router appearing), then the order will be wrong again.
-         *
-         * [1] https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/1021 */
-    }
+    plat_addresses = nm_platform_lookup_clone(
+        self,
+        nmp_lookup_init_object(&lookup, NMP_OBJECT_TYPE_IP_ADDRESS(IS_IPv4), ifindex),
+        NULL,
+        NULL);
 
     if (nm_g_ptr_array_len(plat_addresses) > 0) {
         /* Delete addresses that interfere with our intended order. */