clean the deprecated func Parallelize

[danielqsj]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

I find the func Parallelize was deprecated in v1.13 by #68403. And no reference in k/k repo.
I think it's safe to clean it in v1.15.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Remove the function Parallelize, please convert to use the function ParallelizeUntil.

[roycaihw]

/assign @cheftako

[danielqsj]

/cc @wgliang @sttts @wojtek-t

[danielqsj]

/retest

[wgliang]

LGTM. But we must also ensure that Parallelize is not called by others. It may also be a good idea to remove the deprecated statement and keep it.
I will leave lgtm to @sttts

[wojtek-t]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: danielqsj, wojtek-t

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[cheftako]

/sig cloud-provider

[cheftako]

I think we need to start having a better policy for handling deprecated APIs than just its major version bump to client-go so we can delete it 1 quarter later. Also no references in K/K is an increasingly poor signal as to usage. Most of our cloud providers are NOT is K/K and hopefully soon none of the cloud providers will be in K/K. Given that most cloud providers are running about two releases behind, this implies that the API will have changed a quarter before the user reasonably has a chance to object.