Disable multiattach for the iSCSI Cinder job

Change-Id: I54ffeecd84552beeabf2a03ee311f8f798eaae07
diff --git a/zuul.d/sp-cinder.yaml b/zuul.d/sp-cinder.yaml
index 720a7db..48d65de 100644
--- a/zuul.d/sp-cinder.yaml
+++ b/zuul.d/sp-cinder.yaml
@@ -17,7 +17,6 @@
         CINDER_ENABLED_BACKENDS: storpool:storpool
         # CINDER_ISCSI_HELPER: tgtadm
         ENABLE_FILE_INJECTION: false
-        ENABLE_VOLUME_MULTIATTACH: true
         TEMPEST_CONCURRENCY: 2
         TEMPEST_EXTEND_ATTACHED_VOLUME: true
         TEMPEST_PLUGINS: cinder-tempest-plugin
@@ -26,8 +25,10 @@
         TEMPEST_VOLUME_VENDOR: StorPool
         # cfg: block
         # TEMPEST_STORAGE_PROTOCOL: storpool
+        # ENABLE_VOLUME_MULTIATTACH: true
         # cfg: iscsi
         TEMPEST_STORAGE_PROTOCOL: iscsi
+        ENABLE_VOLUME_MULTIATTACH: false
         USE_PYTHON3: True
         # PYTHON3_VERSION: 3.6
       devstack_local_conf: