Fix policy rules for adding and removing router interfaces

Currently "add_router_interface" and "remove_router_interface"
policy rules have the "update_router" prefix and thus are never
enforced. Removing the prefix activates the rules.

Also moved some rules, so that all router-related rules are
now grouped together.

Closes-Bug: 1356678
Change-Id: Ib6cc45f2c6d0c7ae394274d6196262529b9fd855
Merge "Fix policy rules for adding and removing router interfaces"