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.

VMSnapshotManagerImpl から開始します。ここではログが実行中の VM に関する誤ったメッセージを報告しているため、PRs 9773 と 3724 で参照されている変更と動作を比較します。異なる PowerFlex プール上に ROOT ディスクと DATA ディスクがある停止中の VM のスナップショットケースを再現します。エラーが VM の実際の状態を報告し、サポート対象の操作が正しく動作すれば完了です。

索引モデルが issue の本文から書いたものです。