Refactor mapping from APF counters to metrics counters

Use EnumMap for APF counters to metrics counters.
It is easier to tell the missing metrics counter if they keep the same declaration sequence

Test: atest NetworkStackTests:com.android.networkstack.metrics.ApfSessionInfoMetricsTest
Change-Id: I5dc0b5c4f8e35ab94cd01324306e314be526bd02
2 files changed