Avoid fade animation when users switch index in hour chart.

Before: https://drive.google.com/file/d/13L1hfbhLiNY_GlT0zzE-SqU3fNXmdta6/view?usp=sharing
After: https://drive.google.com/file/d/1l75m1gzGBcy41SFHJvkcDiwaeZo0Rzpj/view?usp=sharing

Test: manually
Bug: 245655904
Change-Id: Iffaf5328b04ffb1f0ff155ecd8c67cd58b9cbfb5

src/com/android/settings/fuelgauge/batteryusage/BatteryChartPreferenceController.java

@@ -695,7 +695,6 @@ public class BatteryChartPreferenceController extends AbstractPreferenceControll
         }
 
         if (visible) {
-            mHourlyChartView.setAlpha(0f);
             mHourlyChartView.setVisibility(View.VISIBLE);
             mHourlyChartView.animate()
                     .alpha(1f)