Remove vendor_available from cargo2android.json. am: 43a62263d0 am: 7c795c45c1 am: 73f3308583

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/libloading/+/2834510

Change-Id: Ie97b423279bc63511da12a590689c1efd86435da
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>