Do not reset colors but only updateBackgroundTint() when isBlurSupported changes

For colorized notifications, all the tints get reset when updateColors() is called. Instead we just want to recalculate the new background colors if needed

Fixes: 406834445
Test: manual
Flag: com.android.systemui.notification_row_transparency
Change-Id: I73bc22e2f5d2557ffefeb948e335d9d98b55a66f