Remove build rule for py2-futures

This package was a backport of concurrent.futures from Python 3 to
Python 2. It is used directly by VTS but this Soong build rule is not.

Bug: 200119288
Test: lunch aosp_bramble-userdebug && m
Change-Id: I24951b8df34262478c400a5e5f00a361e04e5ebe
1 file changed