Update StringUtil#formatElapsedTime method (2/3)

- Update the usage and the test case
 - Update discharging string to follow new string doc

Bug: 183689347
Test: make RunSettingsRoboTests
Change-Id: I1e14e7da8cb02755d8cf6e12626a0d94fad87121

tests/robotests/src/com/android/settings/wifi/details2/WifiDetailPreferenceController2Test.java

@@ -579,7 +579,11 @@ public class WifiDetailPreferenceController2Test {
                 ZoneId.of("Europe/London"));
         doShouldShowRemainingTimeTest(fakeNow, timeRemainingMs);
         final String expectedSummary = mContext.getString(R.string.wifi_time_remaining,
-                StringUtil.formatElapsedTime(mContext, timeRemainingMs, false /* withSeconds */));
+                StringUtil.formatElapsedTime(
+                        mContext,
+                        timeRemainingMs,
+                        false /* withSeconds */,
+                        false /* collapseTimeUnit */));
         final InOrder inOrder = inOrder(mMockHeaderController);
         inOrder.verify(mMockHeaderController).setSecondSummary(expectedSummary);