Remove divider line for battery card preference

Use CardPreference directly here instead of preference category
Also clean up code and test a little bit.

Bug: 119618813
Test: RunSettingsRoboTests
Change-Id: I3ee2313c10e6e2e34609137f3dcb0391104377d5

src/com/android/settings/fuelgauge/batterytip/tips/BatteryTip.java

@@ -147,14 +147,11 @@ public abstract class BatteryTip implements Comparable<BatteryTip>, Parcelable {
      */
     public abstract void log(Context context, MetricsFeatureProvider metricsFeatureProvider);
 
-    public Preference buildPreference(Context context) {
-        Preference preference = new CardPreference(context);
-
-        preference.setKey(getKey());
+    public void updatePreference(Preference preference) {
+        final Context context = preference.getContext();
         preference.setTitle(getTitle(context));
         preference.setSummary(getSummary(context));
         preference.setIcon(getIconId());
-        return preference;
     }
 
     public boolean shouldShowDialog() {