Fix issue with fontScale changes not taking effect

If a configuration change occurs, and an underlying ResourcesImpl is
swapped out under a Resources object, the DisplayMetrics cached by
TypedArray will be stale and not up-to-date.

Bug: 34120637
Test: cts/hostsidetests/services/activityandwindowmanager/util/run-test CtsServicesHostTestCases android.server.cts.ActivityManagerConfigChangeTests
Change-Id: Id78a6d259250950387c2e95c4a2292fdd095c7af