Disable DND status change notification on watches.

In some situations the watch may show notification when the zen mode (do
not disturb) has changed. However, when this happens clicking on the
notification has no effect as outlined in the bug report. We've
determined that we do not want this notification to ever appear on a
watch.

Bug: 74178001
Change-Id: I68502a83a0914a6aea50ef99b0a3e28270689e0d