CTS: Support force-stop IME package for background users

This corresponds to the framework change [1].

 [1]: Ib953d7968ea3170865f82508d616ffc4e8e91d7c

Bug: 350386877
Fix: 352758479
Test: atest CtsInputMethodInstallTestCases:ForceStopTest
Flag: android.view.inputmethod.concurrent_input_methods
Change-Id: Ia19d5a578297eaf9dcd344822352feda71781bb8