Fix quoting in zuul for tempest plugins

Something has changed and the quoting used in the zuul jobs
configuration no longer works[1]. This patch removes the excess
quoting.

[1] http://logs.openstack.org/61/665861/6/check/ \
    octavia-v2-dsvm-noop-api/dac4dba/job-output.txt.gz \
    #_2019-06-26_14_13_23_428457

Change-Id: Ib5f55a8885e8f5d39af9f464b2bb71d4bde599f0
diff --git a/zuul.d/jobs.yaml b/zuul.d/jobs.yaml
index 4692d82..8e112d6 100644
--- a/zuul.d/jobs.yaml
+++ b/zuul.d/jobs.yaml
@@ -49,7 +49,7 @@
       - ^releasenotes/.*$
     vars:
       devstack_localrc:
-        TEMPEST_PLUGINS: "'/opt/stack/octavia-tempest-plugin'"
+        TEMPEST_PLUGINS: /opt/stack/octavia-tempest-plugin
         USE_PYTHON3: true
       devstack_local_conf:
         post-config:
@@ -140,7 +140,7 @@
           MULTI_HOST: 1
           SERVICE_HOST: "{{ hostvars['controller']['nodepool']['private_ipv4'] }}"
           HOST_IP: "{{ hostvars['controller']['nodepool']['private_ipv4'] }}"
-          TEMPEST_PLUGINS: "'/opt/stack/octavia-tempest-plugin'"
+          TEMPEST_PLUGINS: /opt/stack/octavia-tempest-plugin
           USE_PYTHON3: true
           # Octavia specific settings
           OCTAVIA_CONTROLLER_IP_PORT_LIST: 192.168.0.3:5555,192.168.0.4:5555