Stop running gate-tempest-dsvm-neutron-src-python-glanceclient-juno

These 2 jobs were running on python-glanceclient for all branches:
- gate-tempest-dsvm-neutron-src-python-glanceclient
- gate-tempest-dsvm-neutron-src-python-glanceclient-juno

Currently the -juno version is blocking glanceclient development due
to a version mismatch (bug 1442682).

Stop running the -juno version: the client is currently capped in global
requirements for stable/juno, and there will be a stable/juno branch for
glanceclient soon, so updates to the glanceclient master branch should
not affect stable/juno.

This is the glanceclient equivalent of this (already merged)
keystoneclient change: https://review.openstack.org/#/c/172662

Change-Id: Ia1b552b935a37a0a19654a3e1d90e22bc485c187
Closes-bug: 1442682

zuul/layout.yaml

@@ -1928,7 +1928,6 @@ projects:
       - name: python3-jobs
       - name: openstack-client-publish-jobs
       - name: check-requirements
-      - name: stable-compat-jobs-one-release
       - name: publish-to-pypi
       - name: pypy-jobs
       - name: lib-forward-testing