Update .gitreview and .zuul.yaml after rename

The repo got moved from x/devstack-plugin-nfs to
openstack/devstack-plugin-nfs, update .gitreview and jobs
for this.

Change-Id: I510655dabea6886a27bec52e83a3cc86bd7ebd15

.gitreview

@@ -1,4 +1,4 @@
 [gerrit]
 host=review.opendev.org
 port=29418
-project=x/devstack-plugin-nfs.git
+project=openstack/devstack-plugin-nfs.git

.zuul.yaml

@@ -23,11 +23,11 @@
         * legacy-tempest-dsvm-full-devstack-plugin-nfs
     timeout: 10800
     required-projects:
-      - opendev.org/x/devstack-plugin-nfs
+      - opendev.org/openstack/devstack-plugin-nfs
     host-vars:
       controller:
         devstack_plugins:
-          devstack-plugin-nfs: https://opendev.org/x/devstack-plugin-nfs
+          devstack-plugin-nfs: https://opendev.org/openstack/devstack-plugin-nfs
     vars:
       devstack_localrc:
         ENABLE_NFS_CINDER: true
@@ -53,11 +53,11 @@
         * legacy-tempest-dsvm-full-devstack-plugin-nfs
     timeout: 10800
     required-projects:
-      - opendev.org/x/devstack-plugin-nfs
+      - opendev.org/openstack/devstack-plugin-nfs
     host-vars:
       controller:
         devstack_plugins:
-          devstack-plugin-nfs: https://opendev.org/x/devstack-plugin-nfs
+          devstack-plugin-nfs: https://opendev.org/openstack/devstack-plugin-nfs
     vars:
       devstack_localrc:
         ENABLE_NFS_CINDER: true