Cancelling Maintenance Mode on NFS Primary Storage fails to remount on KVM hosts

### problem

When a KVM-based NFS Primary Storage is taken out of Maintenance Mode, the CloudStack management state transitions back to "Up," but the actual mount point is not restored on the KVM hosts. This results in a silent failure where the storage is logically available in the UI but physically inaccessible on the hypervisor.

Below is the error seen in the KVM agent log

```
2026-02-23 14:09:31,922 INFO [kvm.storage.LibvirtStorageAdaptor] (AgentRequest-Handler-3:[]) (logid:5f0c1bd2) Found existing defined storage pool b96dc55f-7075-3183-bcef-a0100e328e88, using it.
2026-02-23 14:09:31,922 DEBUG [utils.script.Script] (AgentRequest-Handler-3:[]) (logid:5f0c1bd2) Executing command [/bin/bash -c mountpoint -q /mnt/b96dc55f-7075-3183-bcef-a0100e328e88 ].
2026-02-23 14:09:31,926 WARN [utils.script.Script] (AgentRequest-Handler-3:[]) (logid:5f0c1bd2) Execution of process [49226] for command [/bin/bash -c mountpoint -q /mnt/b96dc55f-7075-3183-bcef-a0100e328e88 ] failed.
2026-02-23 14:09:31,926 DEBUG [utils.script.Script] (AgentRequest-Handler-3:[]) (logid:5f0c1bd2) Exit value of process [49226] for command [/bin/bash -c mountpoint -q /mnt/b96dc55f-7075-3183-bcef-a0100e328e88 ] is [32].
2026-02-23 14:09:31,926 WARN [utils.script.Script] (AgentRequest-Handler-3:[]) (logid:5f0c1bd2) Process [49226] for command [/bin/bash -c mountpoint -q /mnt/b96dc55f-7075-3183-bcef-a0100e328e88 ] encountered the error: [32].
2026-02-23 14:09:31,926 ERROR [kvm.storage.LibvirtStorageAdaptor] (AgentRequest-Handler-3:[]) (logid:5f0c1bd2) libvirt failed to mount storage pool b96dc55f-7075-3183-bcef-a0100e328e88 at /mnt/b96dc55f-7075-3183-bcef-a0100e328e88
2026-02-23 14:09:31,928 DEBUG [cloud.agent.Agent] (AgentRequest-Handler-3:[]) (logid:5f0c1bd2) Seq 1-2670916054007415034: { Ans: , MgmtId: 32987999634307, via: 1, Ver: v1, Flags: 10, [{"com.cloud.agent.api.Answer":{"result":"false","details":"Failed to create storage pool: libvirt failed to mount storage pool b96dc55f-7075-3183-bcef-a0100e328e88 at /mnt/b96dc55f-7075-3183-bcef-a0100e328e88","wait":"0","bypassHostMaintenance":"false"}}] }
```

### versions

4.22

### The steps to reproduce the bug

1. Navigate to Infrastructure > Primary Storage.

2. Select an NFS Primary Storage and click Enable Maintenance Mode.

3. Wait for the storage state to transition to Maintenance.

4. Click Cancel Maintenance Mode.

5. Observe the status in the UI (it returns to Up) and check the mount status on the KVM host via mount -l.

### What to do about it?

Current Workaround:
The issue currently requires manual intervention on the KVM host to restore connectivity:

Restarting the libvirtd service.

Executing virsh pool-destroy to force a re-initialization.

Required Fix:
The system should automatically ensure the NFS share is properly remounted and the libvirt pool is started when Maintenance Mode is cancelled, without requiring manual host-level commands.

从日志中显示的 KVM agent 的 LibvirtStorageAdaptor 路径开始，跟踪 NFS Primary Storage 离开 Maintenance Mode 时发生的情况。重现取消步骤，然后验证共享已挂载，并且 libvirt pool 在 KVM host 上无需手动命令即可启动；使用 mount -l 检查挂载状态。

由索引模型根据 Issue 内容生成。