Minor changes on AccessibilityManagerService for visible bg users:

- Don't call switchUser() on restoreCurrentUser...() if not needed.
- Improved logs.

Test: atest CtsUiAutomationTestCases android.app.cts.InstrumentationTest
Test: atest --user-type secondary_user_on_secondary_display CtsUiAutomationTestCases

Bug: 271188189

Change-Id: Ic0e84d53f8a6b20ad028f59149673a1178faaff2