Revert "Migrate mistral-specs to zuul v3"
Revert "Migrate mistral-specs to zuul v3"

These jobs should all stay in project-config.
Read https://docs.openstack.org/infra/manual/zuulv3.html (with just updated instructions merging) on what to migrate - and what not.

This repo does not need  a zuul.yaml file.

This reverts commit bb577d358e0326b2fa61f7477053052b8130038a.

Change-Id: I84bd00d1335bef2356cb9eb2ec201bd107387a9e

openstack/mistral-specs