Switch from 32GB to 16GB nodes for jobs requiring more ram

Also use osh-infra-gate-runner for tls job instead of non-existent
osh-gate-runner.

Change-Id: I3c1105422307fda5b014fc17bcdfe24999ce97eb
Signed-off-by: Andrii Ostapenko <andrii.ostapenko@att.com>

zuul.d/jobs-openstack-helm.yaml

@@ -287,8 +287,7 @@
 - job:
     name: openstack-helm-tls
     parent: openstack-helm-chart-deploy
-    run: tools/gate/playbooks/osh-gate-runner.yaml
-    nodeset: openstack-helm-single-32GB-node
+    nodeset: openstack-helm-single-16GB-node
     vars:
       osh_params:
         openstack_release: stein
@@ -407,7 +406,7 @@
     name: openstack-helm-tungsten-fabric
     parent: openstack-helm-compute-kit
     timeout: 9600
-    nodeset: openstack-helm-single-32GB-node
+    nodeset: openstack-helm-single-16GB-node
     roles:
       - zuul: openstack/openstack-helm-infra
     required-projects: