Fix non responding slice toggling problem.

The issue happens when users are toggling slices. Sometimes the toggle
doesn't work as expected because the pending intent of the toggle action
seems to be canceled for some reasons.

Hence, we replace FLAG_CANCEL_CURRENT with FLAG_UPDATE_CURRENT to prevent from
getting PendingIntent.CancelExcpetion from SliceActionView when toggling
slices.

Note that this change would only apply on Wifi, MobileData, Flashlight
and Bluetooth Slices.

Bug: 140719905
Test: rebuild and switch toggles
Change-Id: Iddbb16ddcbcf97b6f6e680b43645c04fbc061f39