Subscriber Id Match Rules won't be exposed as system Api.
Any caller who references NetworkTemplate#SUBSCRIBER_ID_MATCH_RULE_*
should use the one in NetworkStatsUtils instead.
And remove the need of the constants as soon as possible.
Test: atest NetworkPolicyManagerServiceTest \
FrameworksNetTests
Bug: 204830222
Change-Id: I363a4440f85f1ca818eaf1125e45b141dd6f0e55