CI: remove quotation marks from TEMPEST_PLUGINS variable

The has stopped working out of a sudden. We should move to tempest_plugins
zuul variable later on, but it is only available since Stein.

Change-Id: I2cc64580b089566e664d54ea2087878b9cce6666
(cherry picked from commit ac0900a)

zuul.d/ironic-jobs.yaml

@@ -31,7 +31,7 @@
         FORCE_CONFIG_DRIVE: True
         INSTALL_TEMPEST: False # Don't install a tempest package globaly
         OVERRIDE_PUBLIC_BRIDGE_MTU: 1400
-        TEMPEST_PLUGINS: "'{{ ansible_user_dir }}/src/opendev.org/openstack/ironic-tempest-plugin'"
+        TEMPEST_PLUGINS: "{{ ansible_user_dir }}/src/opendev.org/openstack/ironic-tempest-plugin"
         VIRT_DRIVER: ironic
         BUILD_TIMEOUT: 720
         IRONIC_BAREMETAL_BASIC_OPS: True
@@ -374,7 +374,7 @@
         Q_PLUGIN: ml2
         SWIFT_ENABLE_TEMPURLS: True
         SWIFT_TEMPURL_KEY: secretkey
-        TEMPEST_PLUGINS: "'{{ ansible_user_dir }}/src/opendev.org/openstack/ironic-tempest-plugin'"
+        TEMPEST_PLUGINS: "{{ ansible_user_dir }}/src/opendev.org/openstack/ironic-tempest-plugin"
         TENANT_VLAN_RANGE: 100:150
         VIRT_DRIVER: ironic
       devstack_plugins: