Deprecate mkbootimg_args.json by fully support "--format=mkbootimg" am: 07c6063146 am: de73fd2a36 am: 54e2cc4c57

Original change: https://android-review.googlesource.com/c/platform/system/tools/mkbootimg/+/1693414

Change-Id: I9cf905f71320430fc5264e84b5a5509cd4eef9b5