Prevent calls to StatusBarManagerInternal from visible background users

Visible background users have access to UI on assigned displays on devices that have config_multiuserVisibleBackgroundUsers enabled. The main use case is Automotive's multi-display Whole Cabin experience where
passengers (modeled as visible background users) can interact with the display in front of them concurrently with the driver (modeled as the the current user) interacting with driver's display.

- Calls to StatusBarManagerInternal trigger callbacks to the registered
  IStatusBar for the current user.
- However, StatusBarManagerInternal APIs can be called from not only
  the current user but also visible background users.
- We should prevent this to ensure that visible background users do not interfere with the current user's experience.

Bug: 332222893
Flag: EXEMPT bugfix
Test: atest MagnificationConnectionManagerTest
      atest WmTests:PhoneWindowManagerTests
(cherry picked from https://partner-android-review.googlesource.com/q/commit:62538ec79f939853bd4ea75e81f4f46204fce72d)

Change-Id: Icdc6515e69e8044cf972a9e14e2fdd7f7a4b6958