Reset blur radius to 0 whenever blur is not supported

Fixes: 391409723
Test: added unit tests
Test: verified manually,
 1. Pull down shade
 2. Enable battery saver
 3. verify background becomes unblurred immediately
Flag: com.android.systemui.bouncer_ui_revamp
Change-Id: I9dd1b5acfda481ce123163cb1688d25e179f85e4