Fix unnecessary main thread assert when background inflating ViewFlippers in notifications.

* Add `assertOnMainThread` param to `View.repeatWhenAttached` with default value of `true`
* Changes `NotificationViewFlipperBinder` to use `assertOnMainThread = false`

Fixes: 432834931
Flag: EXEMPT bugfix
Test: manual
Change-Id: Ief7e0deec4d11f8cd9e674b3b4cca8b9e79f740a