Clear FLAG_STARTING_WINDOW_TRANSFER_RECIPIENT properly

This CL removes FLAG_STARTING_WINDOW_TRANSFER_RECIPIENT when removing
starting window. Otherwise, it will make us to abort any transitions
that the activity is involved.

Fix: 279800916
Test: 1. Open WhatsApp.
      2. Open a conversation.
      3. See if there is an animation while opening the conversation.
Change-Id: I138af8492d1c57f9053cbb27c3c1748989353fd7