Incorrect policy routing ip rule cleanup on reload with ip4table/ip6table change

interface_change_config() changes the ip4table and ip6table fields of if_old here: https://github.com/openwrt/netifd/blob/777f5942fa7d6245f6ad29daa1daecc400344d37/interface.c#L1369-L1370. After the update, interface_ip_set_enabled(..., false) and interface_set_prefix_address() will clean up a number of implicitly created ip rules (set_ip_source_policy() and set_ip_lo_policy()) before setting them up again, but the cleanup will attempt to delete rules with the new ip[46]table instead of its old value, so the deletion fails. Only a full network restart will clean up rules properly.

I don't know the code well enough to propose a proper fix; the following ideas did not work out so far:

• Set interface_ip_set_enabled(..., false) before updating the fields (probably possible in the reload_ip == true case, unclear if the reload == true case can be made to work)
• Delete rule with 'unspecified' table lookup (there may be multiple rules that only differ by the table number)
• Store the table numbers used for the last rule creation in the interface_ip_settings, so the same table can be used for cleanup (possible for interface_ip_set_enabled(), looks more complicated for ``interface_set_prefix_address()`

It is unclear to me if a combination of the above ideas could be sufficient for a fix, or if more precise tracking of created rules would be required for cleanup.

Start in interface.c at interface_change_config(), especially the ip4table/ip6table updates around lines 1369-1370, and trace interface_ip_set_enabled(), interface_set_prefix_address(), set_ip_source_policy(), and set_ip_lo_policy(). Verify how reload cleanup identifies policy rules, then ensure rules created with the previous table values are removed before or during reconfiguration so a full network restart is not required.