Fix kolla config for host discovery job

Kolla copies the script to bin and sets the proper permissions to it but
then it tries to execute it from the mount point where only root has
permission.

```
❯ oc logs --follow nova-cell1-host-discover-8vtfm
+ sudo -E kolla_set_configs
sudo: unable to send audit message: Operation not permitted
INFO:__main__:Loading config file at /var/lib/kolla/config_files/config.json
INFO:__main__:Validating config file
INFO:__main__:Kolla config strategy set to: COPY_ALWAYS
INFO:__main__:Copying service configuration files
INFO:__main__:Deleting /etc/nova/nova.conf
INFO:__main__:Copying /var/lib/openstack/config/nova-blank.conf to /etc/nova/nova.conf
INFO:__main__:Setting permission for /etc/nova/nova.conf
INFO:__main__:Copying /var/lib/openstack/config/01-nova.conf to /etc/nova/nova.conf.d/01-nova.conf
INFO:__main__:Setting permission for /etc/nova/nova.conf.d/01-nova.conf
INFO:__main__:Copying /var/lib/openstack/bin/host_discover.sh to /bin/host_discover.sh
INFO:__main__:Setting permission for /bin/host_discover.sh
INFO:__main__:Writing out command to execute
++ cat /run_command
+ CMD=/var/lib/openstack/bin/host_discover.sh
+ ARGS=
+ sudo kolla_copy_cacerts
sudo: unable to send audit message: Operation not permitted
+ [[ ! -n '' ]]
+ . kolla_extend_start
+ echo 'Running command: '\''/var/lib/openstack/bin/host_discover.sh'\'''
Running command: '/var/lib/openstack/bin/host_discover.sh'
+ umask 0022
+ exec /var/lib/openstack/bin/host_discover.sh
/usr/local/bin/kolla_start: line 22: /var/lib/openstack/bin/host_discover.sh: Permission denied
```

So this patch fixed the kolla config to execute the script from /bin

templates/nova-manage/config/host-discover-config.json

@@ -1,5 +1,5 @@
 {
-    "command": "/var/lib/openstack/bin/host_discover.sh",
+    "command": "/bin/host_discover.sh",
     "config_files": [
         {
             "source": "/var/lib/openstack/config/nova-blank.conf",