Set title for privacy dialog

a11y services will try to guess the title of a window if it's empty,
usually assigning the title of the first element. As we don't want that,
we explicitly give it a title. This is not visible in UI, and only
available when using a11y descriptions.

Test: manual
Test: atest PrivacyDialogTest
Fixes: 208954254
Change-Id: Ic2042028bed58e369456442e6f6de0965163bee2