Truncate ShortcutInfo Id

Creating Conversation with a ShortcutId longer than 65_535 (max unsigned short), we did not save the conversation settings into the notification_policy.xml due to a restriction in FastDataOutput.
This put us to a state where the user changing the importance or turning off the notifications for the given conversation had no effect on notification behavior.

Fixes: 273729476
Test: atest ShortcutManagerTest2
Test: Create a test app which creates a Conversation with a long shortcutId. Go to the Conversation Settings and turn off Notifications. Post a new Notification to this Conversation and see if it is displayed.
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:ab0c8ac5b47509a71f27c4e5e9ce104d51bab0a8)
Merged-In: I2617de6f9e8a7dbfd8fbeff589a7d592f00d87c5
Change-Id: I2617de6f9e8a7dbfd8fbeff589a7d592f00d87c5