Incorrect error message while creating instance snapshot without memory for a stopped VM

### problem

Incorrect error message while creating instance snapshot without memory for a stopped VM (ROOT & DATA disk on different PowerFlex pools)

```
2026-04-10 09:43:05,535 DEBUG [c.c.v.s.VMSnapshotManagerImpl] (qtp698741991-25:[ctx-8948ca15, ctx-1e54ecb4]) (logid:ea105dce) Creating a snapshot of a running KVM Instance without memory is not supported
2026-04-10 09:43:05,536 INFO [c.c.a.ApiServer] (qtp698741991-25:[ctx-8948ca15, ctx-1e54ecb4]) (logid:ea105dce) Failed to create Instance Snapshot: Creating a snapshot of a running KVM Instance without memory is not supported
```

### versions

ACS 4.20.3 RC4 + Advanced Zone + KVM hypervisor

Should exist with 4.20.1 & 4.20.2 as well, as per the changes here:
https://github.com/apache/cloudstack/pull/9773/changes#diff-7d772616388f0b97219416327c6db1bcad3c162d0271f245ee903198913aa0d3

### The steps to reproduce the bug

1. Deploy a VM with data disk (ROOT & DATA disk on different PowerFlex pools)
2. Stop the VM
3. Take VM snapshot

### What to do about it?

Expecting correct state of the VM in the error message.

Instance snapshots without memory is supported with PowerFlex volumes when all volumes are on the PowerFlex storage and different pools (this seems broken here: https://github.com/apache/cloudstack/pull/3724/changes#diff-705d7f4f3bd1b9d599a38327738fab759b6f6a925f405cbbb7de7bef9b586be2) - now, it is supported when all the volumes are on the same PowerFlex pool only.

从 VMSnapshotManagerImpl 开始，该处的日志报告了错误的运行中 VM 消息，并将其行为与 PRs 9773 和 3724 中引用的更改进行比较。使用位于不同 PowerFlex 池中的 ROOT 和 DATA 磁盘，复现已停止 VM 的快照场景；当错误报告 VM 的实际状态且受支持的操作能够正常运行时，即表示完成。

由索引模型根据 Issue 内容生成。