Use useTestRamdisk to determine the vendor image to use

If true, use vendor_boot-test-harness.img.
Otherwise, use vendor_boot-debug.img.

BUG=b:427595254
TEST=None

Change-Id: I887c7ce406cd592d00b76d89e02779e710ef4897
Reviewed-on: https://chromium-review.googlesource.com/c/infra/infra/+/7123461
Reviewed-by: Kazuhiro Inaba <kinaba@chromium.org>
Commit-Queue: Judy Wu <jinrongwu@google.com>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77431}
NOKEYCHECK=True
GitOrigin-RevId: d69c65d6ef12b087f3f1679beef383ac61eb62cb

• cros/cmd/provision/common-utils/cross-over/full_os_image_state.go[diff]