Fix the enforcing method to pass current user for visible background users

To verify if the calling user is the visible background user, we use the
UserManagerService#enforceCurrentUserIfVisibleBackgroundEnabled method.
This method requires the current user to be passed as a parameter.

Bug: 373274137
Flag: EXEMPT bugfix
Test: atest FrameworksUiServicesTests:com.android.server.UiModeManagerServiceTest
Test: atest CtsAppTestCases:UiModeManagerTest
Test: atest --user-type secondary_user CtsAppTestCases:UiModeManagerTest
Test: atest --user-type secondary_user_on_secondary_display CtsAppTestCases:UiModeManagerTest
(cherry picked from https://partner-android-review.googlesource.com/q/commit:87566613c12b7f44bd9465c6226d7b542ea1e3a2)

Change-Id: I3d24a483e3f563778d1e49971a35dd74895c79d1