Fix Hyper-V Stop-VM to use TurnOff on timeout/failure

[vyadavmsft]

When Stop-VM -Force times out or fails, VMs remain running and cause issues for subsequent operations. This implements a fallback mechanism.

Changes:

• Wrap Stop-VM -Force in try-except to catch failures
• On failure, attempt Stop-VM -TurnOff to forcefully power off the VM
• Log warning when falling back to TurnOff
• Log error and re-raise if both methods fail

This ensures VMs don't get stuck in running state when graceful shutdown hangs or times out, preventing leftover VMs on the server.

[squirrelsc]

@LiliDeng LGTM