Merge "Export BOARD_VENDOR_BOOTIMAGE_PARTITION_SIZE to Soong" into main am: e56edd1c1e

Original change: https://android-review.googlesource.com/c/platform/build/+/3434902

Change-Id: I41f6ddd83bd2f2aa8d5a46d1daea6935e4862e35
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>