Fall back to en-US if localized bitmap is missing for a locale

We used to show the image for the last locale or an empty image, if
the localized image is missing for a specific locale. As the default
english one is more meaningful to users, we should just error out and
fall back to use the default locale when the image loading fails.

Bug: 128934634
Test: run graphic test, locale test
Change-Id: Iafd3e8466aec63b4952d1959b2a3d37e358677d4