Sharesheet - Give shortcut api results priority

Limit the direct share list to MAX_SERVICE_COUNT and discard any
results over that. Do not furthur rank results from App Prediction
Service, and also give other shortcut results priority over older
direct share targets

Bug: 126568576
Test: atest ChooserActivityTest
Change-Id: I2e2d53134273583a504c71ae4daa9f1db951b164