[MS37] Replace NetworkStatsManagerInternal usages in NPMS

This is done by:
1. Add NetworkStatsManagerInternal APIs directly from
   NetworkStatsManager, these APIs are needed by NPMS.
2. Replace all usages with these APIs.
3. Delete NetworkStatsManagerInternal implementation.

Test: atest FrameworksNetTests NetworkPolicyManagerServiceTest
Bug: 204830222
CTS-Coverage-Bug: 213124616
Change-Id: If51b6676915e3a0a8a9f95221d735306911442fc
3 files changed
tree: a0e43ac5d0957e7b3342a89cc39ca003ee64a155
  1. core/
  2. framework/
  3. framework-t/
  4. service-t/
  5. services/
  6. tests/