Refactor updating rules for all apps in NetworkPolicyManagerService

This gives more flexibility to the user (e.g. will allow restricted
networking mode to update all firewall rules at once) and removes some
unnecessary code.

Bug: 170322816
Bug: 157505406
Test: atest NeworkPolicyManagerServiceTest
Change-Id: Id31a60ad37c280bfb4f5bacf63aafe9de28c5e62