Set default locale in the testing environment to avoid flaky test

from the error message, looks like some testing environment cannot get the default locale settings to cause it crash. we will et the default locale before testing to avoid such condition.

Bug: 188947451
Test: make SettingsgRoboTests
Change-Id: I6ec9abba41d72c205426df8710eae5b83a841f46
diff --git a/tests/robotests/src/com/android/settings/fuelgauge/BatteryChartPreferenceControllerTest.java b/tests/robotests/src/com/android/settings/fuelgauge/BatteryChartPreferenceControllerTest.java
index 606dc19..154673d 100644
--- a/tests/robotests/src/com/android/settings/fuelgauge/BatteryChartPreferenceControllerTest.java
+++ b/tests/robotests/src/com/android/settings/fuelgauge/BatteryChartPreferenceControllerTest.java
@@ -93,8 +93,9 @@
 
     @Before
     public void setUp() {
-        org.robolectric.shadows.ShadowSettings.set24HourTimeFormat(false);
         MockitoAnnotations.initMocks(this);
+        Locale.setDefault(new Locale("en_US"));
+        org.robolectric.shadows.ShadowSettings.set24HourTimeFormat(false);
         mFeatureFactory = FakeFeatureFactory.setupForTest();
         mMetricsFeatureProvider = mFeatureFactory.metricsFeatureProvider;
         mContext = spy(RuntimeEnvironment.application);
diff --git a/tests/robotests/src/com/android/settings/fuelgauge/ConvertUtilsTest.java b/tests/robotests/src/com/android/settings/fuelgauge/ConvertUtilsTest.java
index 0c96b8e..a6a9f19 100644
--- a/tests/robotests/src/com/android/settings/fuelgauge/ConvertUtilsTest.java
+++ b/tests/robotests/src/com/android/settings/fuelgauge/ConvertUtilsTest.java
@@ -60,6 +60,8 @@
         mContext = spy(RuntimeEnvironment.application);
         mFeatureFactory = FakeFeatureFactory.setupForTest();
         mPowerUsageFeatureProvider = mFeatureFactory.powerUsageFeatureProvider;
+        Locale.setDefault(new Locale("en_US"));
+        org.robolectric.shadows.ShadowSettings.set24HourTimeFormat(false);
     }
 
     @Test