Disable unused Python 2 variant. am: 5dfda218df am: 4487a904e1

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

Change-Id: I0417d937d465d3aef23f8cfdaf61656cb98ffcb3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>