repack_bootimg: replaces the ramdisk file directly am: d0d261f3b0 am: 0639d39c12 am: d6c8be1c86 am: 21e91e2a7a am: 5423822727

Original change: https://android-review.googlesource.com/c/platform/system/tools/mkbootimg/+/1696925

Change-Id: Ib735b5c59b48f084fb5c5b5c645d23a940524db1