Disable unused Python 2 variant. am: f3568df232 am: 08959a10d4 am: 5908c1292b am: 9fd4945fa5

Original change: https://android-review.googlesource.com/c/platform/external/python/google-auth-library-python/+/2221605

Change-Id: If2c13fc0625230f3806f4d6d1929d3ec936e5fca
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>