Wrong instance xml for a volume booted instances when created using REST API

[Abhijeet Patra]

Description
===========
The instance XML shows that the instance is nova booted while it is volume booted when created using the below-mentioned steps.

Steps to reproduce
==================
- I used the below curl command to create a volume booted instance which worked fine and the instance got created:

```
(overcloudtraindev2) [stack@undercloud16dev2 ~]$ curl -g -i -X POST https://overcloudtraindev2.trilio.local:13774/v2.1/servers \
> -H "Accept: application/json" \
> -H "Content-Type: application/json" \
> -H "OpenStack-API-Version: compute 2.79" \
> -H "User-Agent: python-novaclient" \
> -H "X-Auth-Token: gAAAAABmQhTkc8YppuCkQZ0A7Vf75FYCwuoM3QVNH46pMDf8QqkZ9YaBmYmCdRNU4_QNVBoLRSV4RFm425qwVk4x--sQwlbjwLaiiSzLmd4spYmnI9MmLqifTt3YDVp_2XjiR0xdnkF8zmdkzfxwX_9Nc2lN77dfqiXXa1zbiiNiZzyr_kx5Fs4" \
> -H "X-OpenStack-Nova-API-Version: 2.79" \
> -d '
> {
> "server": {
> "name": "temp_vol_booted_curl",
> "imageRef": "f2285517-a996-40d3-b331-c8214ec66b77",
> "flavorRef": "a483e589-f191-42be-9890-2d7a5e97ba78",
> "min_count": 1,
> "max_count": 1,
> "block_device_mapping_v2": [
> {
> "uuid": "f2285517-a996-40d3-b331-c8214ec66b77",
> "boot_index": "0",
> "source_type": "image",
> "destination_type": "volume",
> "volume_size": 10
> }
> ],
> "networks": [
> {
> "uuid": "6021f51f-568a-4f8e-b5a9-cfdf92c495eb"
> }
> ]
> }
> }'
HTTP/1.1 202 Accepted
Date: Mon, 13 May 2024 13:54:24 GMT
Server: Apache
Content-Length: 418
location: https://overcloudtraindev2.trilio.local:13774/v2.1/servers/8cae4622-042a-4db3-a508-6b93d8deb4b7
OpenStack-API-Version: compute 2.79
X-OpenStack-Nova-API-Version: 2.79
Vary: OpenStack-API-Version,X-OpenStack-Nova-API-Version
x-openstack-request-id: req-17facfdb-d0c7-4304-86a3-80af01b81c42
x-compute-request-id: req-17facfdb-d0c7-4304-86a3-80af01b81c42
Content-Type: application/json

{"server": {"id": "8cae4622-042a-4db3-a508-6b93d8deb4b7", "links": [{"rel": "self", "href": "https://overcloudtraindev2.trilio.local:13774/v2.1/servers/8cae4622-042a-4db3-a508-6b93d8deb4b7"}, {"rel": "bookmark", "href": "https://overcloudtraindev2.trilio.local:13774/servers/8cae4622-042a-4db3-a508-6b93d8deb4b7"}], "OS-DCF:diskConfig": "MANUAL", "security_groups": [{"name": "default"}], "adminPass": "zXBbyJanp2FH"}}(overcloudtraindev2) [stack@undercloud16dev2 ~]$
(overcloudtraindev2) [stack@undercloud16dev2 ~]$
(overcloudtraindev2) [stack@undercloud16dev2 ~]$ openstack server show 8cae4622-042a-4db3-a508-6b93d8deb4b7
+-------------------------------------+----------------------------------------------------------------------------------+
| Field | Value |
+-------------------------------------+----------------------------------------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | nova |
| OS-EXT-SRV-ATTR:host | overcloudtraindev2-novacompute-0.trilio.local |
| OS-EXT-SRV-ATTR:hostname | temp-vol-booted-curl |
| OS-EXT-SRV-ATTR:hypervisor_hostname | overcloudtraindev2-novacompute-0.trilio.local |
| OS-EXT-SRV-ATTR:instance_name | instance-000001a7 |
| OS-EXT-SRV-ATTR:kernel_id | |
| OS-EXT-SRV-ATTR:launch_index | 0 |
| OS-EXT-SRV-ATTR:ramdisk_id | |
| OS-EXT-SRV-ATTR:reservation_id | r-jrlmxqsw |
| OS-EXT-SRV-ATTR:root_device_name | /dev/vda |
| OS-EXT-SRV-ATTR:user_data | None |
| OS-EXT-STS:power_state | Running |
| OS-EXT-STS:task_state | None |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2024-05-13T13:54:39.000000 |
| OS-SRV-USG:terminated_at | None |
| accessIPv4 | |
| accessIPv6 | |
| addresses | internal=10.10.10.130 |
| config_drive | |
| created | 2024-05-13T13:54:25Z |
| description | None |
| flavor | disk='1', ephemeral='0', , original_name='cirros', ram='64', swap='0', vcpus='1' |
| hostId | 366f2ccb62c960efb28dc6035bb77b5719dbb1ed35e75fafb34da83a |
| host_status | UP |
| id | 8cae4622-042a-4db3-a508-6b93d8deb4b7 |
| image | cirros (f2285517-a996-40d3-b331-c8214ec66b77) |
| key_name | None |
| locked | False |
| locked_reason | None |
| name | temp_vol_booted_curl |
| progress | 0 |
| project_id | 3df2e8acc97846a591048a5b54cade51 |
| properties | |
| security_groups | name='default' |
| server_groups | [] |
| status | ACTIVE |
| tags | [] |
| trusted_image_certificates | None |
| updated | 2024-05-13T13:54:39Z |
| user_id | 27be5b757cea44fda73b7381e5144425 |
| volumes_attached | delete_on_termination='False', id='6340c7e6-08db-4554-b871-95339ddb1acc' |
+-------------------------------------+----------------------------------------------------------------------------------+
(overcloudtraindev2) [stack@undercloud16dev2 ~]$
```

Expected result
===============
The metadata from the instance XML should not have
```
<nova:root type="image" uuid="f2285517-a996-40d3-b331-c8214ec66b77"/>
```

Actual result
=============
The metadata from the instance XML says the instance is image booted

```
<metadata>
    <nova:instance xmlns:nova="http://openstack.org/xmlns/libvirt/nova/1.0">
      <nova:package version="20.6.2-2.20230814165223.el8ost"/>
      <nova:name>temp_vol_booted_curl</nova:name>
      <nova:creationTime>2024-05-13 13:54:35</nova:creationTime>
      <nova:flavor name="cirros">
        <nova:memory>64</nova:memory>
        <nova:disk>1</nova:disk>
        <nova:swap>0</nova:swap>
        <nova:ephemeral>0</nova:ephemeral>
        <nova:vcpus>1</nova:vcpus>
      </nova:flavor>
      <nova:owner>
        <nova:user uuid="27be5b757cea44fda73b7381e5144425">admin</nova:user>
        <nova:project uuid="3df2e8acc97846a591048a5b54cade51">admin</nova:project>
      </nova:owner>
      <nova:root type="image" uuid="f2285517-a996-40d3-b331-c8214ec66b77"/>
    </nova:instance>
  </metadata>

```

Environment
===========
1. Openstack : Train
```
[root@overcloudtraindev2-novacompute-0 /]# rpm -qa | grep nova
python3-novaclient-15.1.1-2.20220111010504.79959ab.el8ost.noarch
openstack-nova-migration-20.6.2-2.20230814165223.el8ost.noarch
openstack-nova-common-20.6.2-2.20230814165223.el8ost.noarch
openstack-nova-compute-20.6.2-2.20230814165223.el8ost.noarch
python3-nova-20.6.2-2.20230814165223.el8ost.noarch
[root@overcloudtraindev2-novacompute-0 /]#
```

2. Which hypervisor did you use?
   libvirt-daemon-kvm-7.0.0-14.8.module+el8.4.0+15255+f7eff4dd.x86_64