Currently, BpfCoordinator only sets the data limit on a given
upstream whenever the first IPv6 rule is created on that
upstream, and clears it whenever the last rule is deleted on that
upstream. It never does this when adding or removing IPv4 rules.
This makes it impossible to offload traffic on IPv4-only
networks.
Fix this by setting the limit when IPv4 rules are created or
deleted as well.
Test: atest TetheringCoverageTests
Manual tests as the follows
Test {add, clear} limit with IPv6-only network [OK]
Test {add} limit with IPv4-only upstream [OK]
TODO:
Test {clear} limit with IPv4-only network. blocked by aosp/1579873
because the IPv4 rules have never deleted.
Change-Id: I5a29bdd18e564318759f617023163e23fb5a3ed0
dc6715c6f8