This change includes:
1. Rename binder interfaces.
2. Use a dedicated class to pass the result of
get{Total|Iface|Uid}Stats, as it is 25% faster than passing
a NetworkStats object through the binder interface.
3. Remove the binder interface only used by the test.
4. Remove NetworkStatsBinderTest on R and S, since the binder
interface is removed, the mainlined service does not run on
those versions and the chance of breaking these tests on
R and S is low.
5. Remove useless TODO comments.
Test: atest FrameworksNetTests:android.net.connectivity.com.android.server.net.NetworkStatsServiceTest \
CtsNetTestCases:android.net.cts.NetworkStatsBinderTest \
FrameworksNetIntegrationTests:com.android.server.net.integrationtests.NetworkStatsIntegrationTest
Bug: 372851500
Bug: 343260158
Change-Id: Ibd79a17218f54f0117d8ef5d7b9ec6073356f923
9fb574d0c3