fix custom resolver activity cts fail

resolver/chooser activities can be overridden in overlay resources

This bug was caused by use hardcoded 'android/com.android.internal.app.ResolverActivity/ChooserActivity' to check fg activity when share test

Test: run cts -m CtsDevicePolicyManagerTestCases -t com.android.cts.devicepolicy.ManagedProfileTest#testResolverActivityLaunchedFromPersonalProfileWithSelectedWorkTab

BUG: 241512605

Change-Id: Ieace63df98504bb2a64b44d18a5e1721c4656198
(cherry picked from commit 9faa94029dce364bf7734a44ad01bfc1b4f27964)