Extend timeout for Biometric Prompt messages when talkback enabled

When talkback is enabled, use
AccessibilityManager.getRecommenededTimeoutMillis to determine length of
time message some remain.

Fixes: 373771867
Fixes: 373778537
Test: Verified manually
Test: atest PromptViewModelTest
Flag: EXEMPT bugfix
Change-Id: Ie7b12f586c5ee9f4a5328b1da42ee00720fa7d7c