LauncherInstrumentation enables even when non-system user

Attempting to run a tapl test while the device is in a secondary user
currently fails because the test app doesn't get enabled for
this secondary user. We fix that (at least one issue with it) in this cl.

Test: make PlatformScenarioTests; adb root && adb install -r -g ${ANDROID_PRODUCT_OUT}/testcases/PlatformScenarioTests/$(get_build_var TARGET_ARCH)/PlatformScenarioTests.apk
adb shell am instrument -w -r -e class android.platform.test.scenario.chrome.OpenApp android.platform.test.scenario/androidx.test.runner.AndroidJUnitRunner
(Do this while the current user is SYSTEM as well as Guest)

Bug: 162454040
Change-Id: If6d8e545b41eb20e3fed2935c39069ce97d8b6cd