Fix shared transitions from work profile

We need to start the fade animation (and prevent the initial
ACTION_CLOSE_SYSTEM_DIALOGS broadcast from dismissing the
screenshot UI).

Flag: SCREENSHOT_WORK_PROFILE_POLICY
Bug: 254518387
Test: manual (visual change; observed that UI fades out as expected
when SCREENSHOT_WORK_PROFILE_POLICY flag is on)

Change-Id: I69e7cd94bf621a28ec2ceb3586db0b80a65278e3