SF: Don't store config ids in RefreshRateStats

Configs IDs can change during runtime, so we shouldn't store
them to calculate the refresh rate stats. Instead we store
only the current refresh rate. Additionally this CL removes
the dependency on RefreshRateConfigs.

Bug: 159590486
Test: atest RefreshRateStatsTest
Change-Id: Id0af0598fb1c72ea4c1328bdb372506f0436b8da