In https://chromium-review.googlesource.com/c/chromium/src/+/1066737 I noticed that many tests inadvertently cause ArcPlayStoreEnabledPreferenceHandler::OnPreferenceChanged() to be called without signin_manager->IsAuthenticaed() to be true, unlike other calls to consent_audtior made by ARC.

For example, on linux-chromeos-rel, these browser_tests:
ArcAppLauncherBrowserTest.ShelfGroup
ArcSessionManagerTest.ManagedAndroidAccount

As well as some unit_tests as per https://ci.chromium.org/p/chromium/builders/luci.chromium.try/linux-chromeos-rel/5795
ArcDefaulAppTest
ArcPlayStoreAppTest
ChromeAppIconTest.ChromeBadging
ChromeLauncherControllerArcDefaultAppsTest
ChromeLauncherControllerWithArcTest
NoteTakingHelperTest

This task is to fix these tests so we can restore the DCHECK / remove the runtime check of signin_manager->IsAuthenticated() in ArcPlayStoreEnabledPreferenceHandler::OnPreferenceChanged()