Add and switch to the newly created opensuse-15 nodeset

opensuse-150 nodeset is referring to openSUSE 15.0, which is still in
maintenance but openSUSE 15.1 has been released already. "opensuse-15"
is going to refer to the "latest openSUSE 15.x" build released and
working for OpenStack going forward, so add this nodeset and use
it by default going forward.

Depends-On: https://review.opendev.org/682882
Change-Id: Ic3f4d6998a66da5226bc95088d7e3c83dfe737ce
(cherry picked from commit 70fca49de7)

.zuul.yaml

@@ -39,10 +39,10 @@
           - controller
 
 - nodeset:
-    name: devstack-single-node-opensuse-150
+    name: devstack-single-node-opensuse-15
     nodes:
       - name: controller
-        label: opensuse-150
+        label: opensuse-15
     groups:
       - name: tempest
         nodes:
@@ -524,10 +524,10 @@
     voting: false
 
 - job:
-    name: devstack-platform-opensuse-150
+    name: devstack-platform-opensuse-15
     parent: tempest-full
-    description: openSUSE 15.0 platform test
-    nodeset: devstack-single-node-opensuse-150
+    description: openSUSE 15.x platform test
+    nodeset: devstack-single-node-opensuse-15
     voting: false
 
 - job:
@@ -619,7 +619,7 @@
         - devstack-ipv6:
             voting: false
         - devstack-platform-centos-7
-        - devstack-platform-opensuse-150
+        - devstack-platform-opensuse-15
         - devstack-platform-fedora-latest
         - devstack-platform-xenial
         - devstack-multinode

stack.sh

@@ -221,7 +221,7 @@ write_devstack_version
 
 # Warn users who aren't on an explicitly supported distro, but allow them to
 # override check and attempt installation with ``FORCE=yes ./stack``
-if [[ ! ${DISTRO} =~ (xenial|artful|bionic|stretch|jessie|f28|f29|opensuse-42.3|opensuse-15.0|opensuse-tumbleweed|rhel7) ]]; then
+if [[ ! ${DISTRO} =~ (xenial|artful|bionic|stretch|jessie|f28|f29|opensuse-15.0|opensuse-15.1|opensuse-tumbleweed|rhel7) ]]; then
     echo "WARNING: this script has not been tested on $DISTRO"
     if [[ "$FORCE" != "yes" ]]; then
         die $LINENO "If you wish to run this script anyway run with FORCE=yes"