StatsManager: @Deprecated always-deprecated fields

When P shipped, StatsManager had some new (introduced in P) APIs that
were already deprecated but had been needed temporarily. No one should
ever have used these APIs when P shipped because they already had
comments instructing the reader that they were deprecated. They were not
marked @Deprecated, however, so this cl does that.

Fixes: 113856561
Fixes: 77648233
Test: still compiles
Test: make ROBOTEST_FILTER=AnomalyConfigJobServiceTest RunSettingsRoboTests
Test: gts-tradefed run gts-dev --module GtsStatsdHostTestCases
Change-Id: I7c5cdc616f806b9aa5a5e4ee4229750973f533ed