Migrate all data usage format use case

Now they are all aligned.

Bug: 321861088
Flag: EXEMPT bug fix
Test: unit test
Change-Id: I1981fd32fd24de7c9eff93e0cd638e862f01b9b9

tests/robotests/src/com/android/settings/datausage/DataUsageUtilsTest.java

@@ -29,7 +29,6 @@ import android.content.Context;
 import android.content.pm.PackageManager;
 import android.net.ConnectivityManager;
 import android.telephony.TelephonyManager;
-import android.util.DataUnit;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -74,14 +73,6 @@ public final class DataUsageUtilsTest {
         assertThat(hasMobileData).isFalse();
     }
 
-    @Test
-    public void formatDataUsage_useIECUnit() {
-        final CharSequence formattedDataUsage = DataUsageUtils.formatDataUsage(
-                mContext, DataUnit.GIBIBYTES.toBytes(1));
-
-        assertThat(formattedDataUsage).isEqualTo("1.00 GB");
-    }
-
     @Test
     public void hasEthernet_shouldQueryEthernetSummaryForUser() throws Exception {
         ShadowPackageManager pm = shadowOf(RuntimeEnvironment.application.getPackageManager());