Use templates for cover and lower-constraints

Use openstack-tox-cover template, this runs the cover job
in the check queue only.

Use openstack-lower-constraints-jobs template

Remove jobs that are part of the templates.

Sort list of templates alphabetically.

Fix tox.ini for cover to work.

Change-Id: Id46f74ab4a8f64f7159effc8fa4d552f8217c498

.zuul.yaml

@@ -1,18 +1,11 @@
 - project:
-    check:
-      jobs:
-        - openstack-tox-lower-constraints
-    gate:
-      jobs:
-        - openstack-tox-lower-constraints
     templates:
+      - check-requirements
+      - openstack-cover-jobs
+      - openstack-lower-constraints-jobs
       - openstack-python-jobs
       - openstack-python35-jobs
-      - publish-openstack-docs-pti
-      - check-requirements
-      - release-notes-jobs-python3
-      - periodic-stable-jobs
       - openstack-python36-jobs
-    post:
-      jobs:
-        - openstack-tox-cover
+      - periodic-stable-jobs
+      - publish-openstack-docs-pti
+      - release-notes-jobs-python3

tox.ini

@@ -21,7 +21,7 @@ commands = flake8
 [testenv:cover]
 basepython = python3
 setenv =
-    PYTHON=coverage run --source $project --parallel-mode
+    PYTHON=coverage run --source oslotest --parallel-mode
 commands =
     stestr run '{posargs}'
     coverage combine