Disable unused Python 2 variant. am: 5dfda218df

Original change: https://android-review.googlesource.com/c/platform/external/python/cryptography/+/2221329

Change-Id: I3943a9a26d70ac9f3a7fc046627d5ca8a0f7d953
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>