Don't hide 1% battery usage apps but show percentage "-" instead.

Bug b/242252864 will be fixed at the same time.

screen_record: https://drive.google.com/open?id=1ycEuazqQZzNWGO8E2Fh3GdgyTEd2Z9s0&authuser=0&resourcekey=0-x9BJJE6932jIv9fFoecjeQ&usp=drive_link

Bug: 262187603
Bug: 242252864
Fix: 262187603
Fix: 242252864
Test: manual
Change-Id: Id1a8b5291d66a38fb86f168d3115ae566e6ec079

tests/robotests/src/com/android/settings/fuelgauge/batteryusage/PowerGaugePreferenceTest.java

@@ -104,4 +104,18 @@ public class PowerGaugePreferenceTest {
         assertThat(mPreferenceViewHolder.findViewById(android.R.id.title).getContentDescription())
                 .isEqualTo(CONTENT_DESCRIPTION);
     }
+
+    @Test
+    public void setPercent_greaterThanThreshold_showNumber() {
+        mPowerGaugePreference.setPercent(99.5);
+
+        assertThat(mPowerGaugePreference.getPercent()).isEqualTo("100%");
+    }
+
+    @Test
+    public void setPercent_lessThanThreshold_showBar() {
+        mPowerGaugePreference.setPercent(0.95);
+
+        assertThat(mPowerGaugePreference.getPercent()).isEqualTo("-");
+    }
 }