Do not set title description for Confirm Activity

The Confirm Lock Activity for Auto-Confirm feature announce
redundant description after confirm the PIN/Password in the
Click Toggle CUJ.
1. The title won't be present on the Confirm Lock
2. Set title for Confirm Lock breaks the a11y requirement

Flag: EXEMPT for fixing a11y bug
Bug: 384628809
Test: Manual enable a11y talkback, go to Settings > Security & Privacy
> Device unlock > Screen lock > Settings > Auto-confirm unlock toggle
> input PIN/Password to dismiss the confirm lock activity
> Ensure no redundant title description announced by talkback

Change-Id: I95fc03aae4fb5dc7500cc18c383dff62b95bc3f1