CI: Scope regular builds to the "public" Zuul tenant

Depends-on: https://gerrit.cesnet.cz/c/ci/project-config/+/2556
Change-Id: If750b4ffd01ae8415cb3035950ad844086321bad
diff --git a/.zuul.yaml b/.zuul.public.yaml
similarity index 100%
rename from .zuul.yaml
rename to .zuul.public.yaml