Update battery settings page loading text

- Update the loading text into empty space text to prevent layout flaky before info loaded

Bug: N/A
Test: atest SettingsRoboTests
Change-Id: I272405f5045a682533a4e9405a9fd91f6c507f7e

src/com/android/settings/fuelgauge/BatteryHeaderPreferenceController.java

@@ -59,9 +59,8 @@ public class BatteryHeaderPreferenceController extends BasePreferenceController
     public void displayPreference(PreferenceScreen screen) {
         super.displayPreference(screen);
         mBatteryUsageProgressBarPref = screen.findPreference(getPreferenceKey());
-        // Set up loading text first to prevent layout flaky before info loaded.
-        mBatteryUsageProgressBarPref.setBottomSummary(
-                mContext.getString(R.string.settings_license_activity_loading));
+        // Set up empty space text first to prevent layout flaky before info loaded.
+        mBatteryUsageProgressBarPref.setBottomSummary(" ");
 
         if (com.android.settings.Utils.isBatteryPresent(mContext)) {
             quickUpdateHeaderPreference();