Fix CPU attribution when power stats collection is enabled

The BatteryUsageStatsTests collects battery usage stats over a short
period of time immediately after a reset, not allowing
PowerStatsCollector to gather enough data organically.
We need to force data collection before generating battery usage stats.

Bug: 313830933
Test: atest CtsStatsdAtomHostTestCases:android.cts.statsdatom.batterystats.BatteryUsageStatsTests
Test: atest PowerStatsTests

Change-Id: I55e3f76975ea86315dd6d166ace96a0db64b271e