Fix Tempest Plugin Registry page for plugins url

There is extra 'openstack/' is added in each plugin url, for example:
- https://opendev.org/openstack/openstack/barbican-tempest-plugin
- https://opendev.org/openstack/x/trio2o

https://docs.openstack.org/tempest/latest/plugin-registry.html

Change-Id: Idc19bedeb171a91079008e79267304158504d932

tools/generate-tempest-plugins-list.sh

@@ -69,7 +69,7 @@ function print_plugin_table {
     i=0
     for plugin in $1; do
         i=$((i+1))
-        giturl="https://opendev.org/openstack/${plugin}"
+        giturl="https://opendev.org/${plugin}"
         printf "%-3s %-${name_col_len}s %s\n" "$i" "${plugin}" "${giturl}"
     done