Unwedge stable branch: stop syncing trove and fix pypy

Remove trove from requirements sync in havana. Trove wasn't actually
part of the integrated release in havana,
so it's not getting actively maintained on the backports. Remove
it from requirements sync to help unwedge stable.

pypy is blocking all requirements merge at the moment, which is
problematic as we've got some changes that should land prior to
icehouse. Implement the work around that fungi posted to IRC by
backporting the tox.ini from master.

Depends on: Iab4ae1efddc4dca38dcd3779dae1a79ddc2b0852

Co-Authored-By: Sean Dague <sean.dague@samsung.com>
Co-Authored-By: Sergey Lukjanov <slukjanov@mirantis.com>
Change-Id: Ib2e2aa2e75e7b7b43e0534eeb62e748d1edc0bc3