Fix max volume count

[huww98]

What type of PR is this?

/kind bug

What this PR does / why we need it:

When deciding the number of supported volumes for the disk driver, we are not counting for the already mounted volumes by the previous instance of this plugin.

This PR partially fixes this by calling DescribeDisks and counting for the disks provisioned by CSI. However, the static PVs are still not counted and would cause fewer volumes can be scheduled to this node.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: huww98
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[k8s-ci-robot]

Hi @huww98. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[mowangdk]

/ok-to-test