Update launch intent flags for settings shortcut widgets.

- earlier changes were made to the intent flags when creating new
settings shortcut to ensure that it is launching a new task. However,
ShortcutManager is actually caching existing shortcut info, and it will
continue to use the existing shortcut info unless we explicitly update
the info.
- when rebooting from build upgrade, we will go through all existing
shortcut to update the launch intent flags to ensure that the shortcut
info is update to date.

Change-Id: Iee2365d9aec64a47b193e3c9be443c252504815b
Fixes: 76395879
Test: make RunSettingsRoboTests