Dismiss Autofill Save UI when a new Activity is launched.

Test: manual verification using Settings
Test: cts-tradefed run commandAndExit cts-dev -m CtsAutoFillServiceTestCases -tandroid.autofillservice.cts.SimpleSaveActivityTest#testDismissSave_byLaunchingNewActivity
Test: cts-tradefed run commandAndExit cts-dev -m CtsAutoFillServiceTestCases -tandroid.autofillservice.cts.LoginActivityTest#testSaveGoesAwayWhenLaunchingNewActivity
Test: cts-tradefed run commandAndExit cts-dev -m CtsAutoFillServiceTestCases

Fixes: 64693551

Change-Id: I323031c7285a4b49f9f0ca06618425a0ab7833da