Delete SwitchToGuestTimer

Feature was never used in production and we felt the experience was not
the right one.  So remove support for it to reduce maintenance burden
and potential for buggy code.

Fixes: 144382004
Test: Boot and see no crashes
Test: Add lock to user and show UserPicker.  Run adb command to put car
into drive, wait 30 seconds and see no changes.
adb shell dumpsys activity service com.android.car inject-vhal-event 0x11400400 8
adb shell dumpsys activity service com.android.car inject-vhal-event 0x11600207 30

Change-Id: I257df02a8f669899c7a49df12815b302ec5965bb