Add setMin for A11y stream slider bar.

Since the volume of accessiblity will not go to 0, add setMin for A11y
stream slider in case it goes to 0 in volume panel.

Bug: 72403580
Test: Add log in onProgressChanged and check A11y stream won't go to 0.
Change-Id: Ie8c88c8a40fad4d281997922df8acb8f446288c7