fix: use dl.k8s.io, not kubernetes-release bucket

[rjsadow]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

There are still references to https://storage.googleapis.com/kubernetes-release instead of https://dl.k8s.io/

dl.k8s.io is the correct advertised download host and will eventually move to be fastly shielding a fully community-owned bucket

ref: kubernetes/k8s.io#2396

Required Items

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Optional Items

• 💥 This PR involves a breaking change. If so, include "BREAKING CHANGE: ...why..." in the commit and PR message.

[rjsadow]

/retest

[rjsadow]

/retest

[Namanl2001]

/retest

[starpit]

thanks for doing this!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rjsadow, starpit

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