Fix standalone upgrade train failure

Post this fix https://review.opendev.org/#/c/727887/1 standalone upgrade
train starts failing.

To confirm the upgrade, user will need to explicitly pass --yes flag
while upgrade.

Closes-Bug: #1881306
Change-Id: I36dc044e86534e6d40bf714eec8360fead315740
Signed-off-by: Bhagyashri Shewale <bshewale@redhat.com>

roles/standalone-upgrade/templates/standalone.sh.j2

@@ -1,9 +1,14 @@
+PROMPT_ANSWER=""
+if openstack tripleo upgrade --help | grep -qe "--yes"; then
+    PROMPT_ANSWER="--yes"
+fi
+
 sudo yum update -y \
     python-tripleoclient \
     openstack-tripleo-common \
     openstack-tripleo-heat-templates
 
-sudo openstack tripleo upgrade \
+sudo openstack tripleo upgrade $PROMPT_ANSWER \
   --templates \
   --local-ip={{ standalone_ip }}/{{ standalone_network_prefix }} \
   -e {{ overcloud_templates_path }}/environments/standalone/standalone-tripleo.yaml \