Remove AVB footer & chained vbmeta image from the loaded boot image am: 543bd94bf0 am: 9823a6530a

Original change: https://android-review.googlesource.com/c/platform/test/vts-testcase/security/+/1953492

Change-Id: Ie16b92b6dd107fa55d8feaff3f9be9c300dd225f