[SB] Increase size of BatteryControllerLog.

The BATTERY_CHANGED intents come in pretty frequently, so we
need a larger buffer size to get a good window of battery
events.

Bug: 433239990
Flag: EXEMPT log change
Test: Trigger some battery events, dump log
Change-Id: Ic28c23fe9442da91a460fe17c70965e3732008d5