[release-1.30] fix: refine GetFreeSpace call on Windows

[andyzhangx]

What type of PR is this?
/kind bug

What this PR does / why we need it:
fix: refine GetFreeSpace call on Windows

cherrypick of #2287

this PR could get rid of expensive powershell command (Get-Item -Path $Env:mount).Target

I0412 11:24:54.552255   21436 utils.go:105] GRPC call: /csi.v1.Node/NodeGetVolumeStats
I0412 11:24:54.552255   21436 utils.go:106] GRPC request: {"volume_id":"/subscriptions/b9d2281e-dcd5-4dfd-9a97-0d50377cdf76/resourceGroups/MC_andy-aks127_andy-aks127_eastus2euap/providers/Microsoft.Compute/disks/pvc-9a2a1408-7661-46d6-ae6f-53f8139d501b","volume_path":"c:\\var\\lib\\kubelet\\pods\\ff7d184e-9672-447e-8036-7c3425f85233\\volumes\\kubernetes.io~csi\\pvc-9a2a1408-7661-46d6-ae6f-53f8139d501b\\mount"}
I0412 11:24:54.552255   21436 utils.go:112] GRPC response: {"usage":[{"available":3183468544,"total":3204378624,"unit":1,"used":20910080}]}

Which issue(s) this PR fixes:

Fixes #

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Special notes for your reviewer:

Release note:

fix: refine GetFreeSpace call on Windows

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx

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[andyzhangx]

/retest

[k8s-ci-robot]

@andyzhangx: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-azuredisk-csi-driver-e2e-migration-windows	4a1656c	link	true	/test pull-azuredisk-csi-driver-e2e-migration-windows
pull-azuredisk-csi-driver-e2e-capz	4a1656c	link	true	/test pull-azuredisk-csi-driver-e2e-capz

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