Merge OTEL metrics with legacy registerer

[zarvd]

What type of PR is this?

/kind feature

What this PR does / why we need it:

To export all metrics in 1 endpoint.

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]

Hi @zarvd. 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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[mainred]

Not quite familiar withe old register we have, but left a comment.
And can you list the OTEL metrics from after merging the metrics from legacy register as a test?

[feiskyer]

/ok-to-test

[zarvd]

/retest

[zarvd]

@cvvz PTAL

[mainred]

/test pull-cloud-provider-azure-e2e-ccm-vmss-capz

[andyzhangx]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx, zarvd

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