Revert "run sandbox-build/publish-docs in periodic pipeline"

This reverts commit 1c3e7447e7046e2bb6d7ae364e4f4c83090c185a.

Reason for revert:

* got both jobs running in periodic pipeline on zuul.opendev.org - https://zuul.opendev.org/t/openstack/buildset/49e30f3c86214d709b4f7e52d0162fed:

  * Job sandbox-build-docs finished successfully.
  * Job sandbox-publish-docs is in enqueued state for 6 hours.

* don't want testing jobs to run regularly in this repo.

Change-Id: I648bee71b10e64ba875ab4421ba3db0e51d72621

zuul.yaml

@@ -9,7 +9,7 @@
     parent: base
     dependencies:
       - sandbox-build-docs
-    run: run.yaml  # just any playbook
+    run: run.yaml
     requires: archive
 
 - project:
@@ -17,10 +17,6 @@
       jobs:
         - sandbox-build-docs
         - sandbox-publish-docs
-    periodic:
-      jobs:
-        - sandbox-build-docs
-        - sandbox-publish-docs
     post:
       jobs:
         - sandbox-build-docs