Value of Global setting "convert.vmware.instance.to.kvm.extra.params.allowed.list" is not appened to the Virt-v2v tool

### problem

Value of Global settng "convert.vmware.instance.to.kvm.extra.params.allowed.list" is not appened to the Virt-v2v tool

### versions

ACS 4.22

### The steps to reproduce the bug

1. Enable the global setting "convert.vmware.instance.to.kvm.extra.params.allowed"

2. Set the convert.vmware.instance.to.kvm.extra.params.allowed to a value say -x

3. Import a vmware from kvm

4. In the import from vmware form, do not select the option "Pass extra parameters to the virt-v2v command on the conversion host"

5. Check the agent logs on the kvm host

The global setting value "extra.params" are not passed to the virt-v2v tool

```
2026-04-13 12:24:59,796 DEBUG [resource.wrapper.LibvirtConvertInstanceCommandWrapper] (AgentRequest-Handler-5:[]) (logid:565d9bad) Executing command [virt-v2v --root first -i ova /mnt/6f0e9b83-ab0d-3cc5-8ac6-189c672fe035/d1fa1750-df2d-44ba-90dc-1a39696137b5/i-2-16-VM/ -o local -os /mnt/6f0e9b83-ab0d-3cc5-8ac6-189c672fe035 -of qcow2 -on 5ed4eabd-058a-400e-a3c8-fa8c215bfb26 -v ].

```

6. The extra param value (-x) is only passed when it's mentioned in the "import from vmware form"

```

2026-04-13 12:31:32,208 DEBUG [resource.wrapper.LibvirtConvertInstanceCommandWrapper] (AgentRequest-Handler-4:[]) (logid:79bdffdc) Executing command [virt-v2v --root first -i ova /mnt/6f0e9b83-ab0d-3cc5-8ac6-189c672fe035/229a4c65-7ebd-42d4-90a2-e51fd2064973/i-2-16-VM/ -o local -os /mnt/6f0e9b83-ab0d-3cc5-8ac6-189c672fe035 -of qcow2 -on 1c906a30-86b1-442a-be0b-39f0cc65abcc -v x

2026-04-13 12:34:02,504 DEBUG [resource.wrapper.LibvirtConvertInstanceCommandWrapper] (AgentRequest-Handler-1:[]) (logid:3ae94f9c) Executing command [virt-v2v --root first -i ova /mnt/6f0e9b83-ab0d-3cc5-8ac6-189c672fe035/b4bc39ad-3065-42c2-b9a7-eec1f6c87454/i-2-16-VM/ -o local -os /mnt/6f0e9b83-ab0d-3cc5-8ac6-189c672fe035 -of qcow2 -on 4addaa01-58bc-43a4-a9d9-b030be5dde46 -v -x ].

```

### What to do about it?

Expected behaviour

The extra parameter value mentioned in the global setting should get populated in the import instance form and admin should be able to select the parameters which could be passed on the the virt-v2v tool

首先复现 VMware 导入工作流，并查看显示不带全局额外参数的 virt-v2v 命令的 agent 日志。跟踪 convert.vmware.instance.to.kvm.extra.params.allowed.list 的加载方式，以及导入表单如何处理额外参数。当该设置填充表单，并且在表单字段未以其他方式选中的情况下，所选值能够传递到 virt-v2v 时，即表示完成。

由索引模型根据 Issue 内容生成。