chore: remove artifacts from cloudbuild

[alexander-ding]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change
/kind bug
/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
Removes artifact listing from cloudbuild.yaml so that postsubmit jobs pass. With v2 we won't be generating the .exe file anymore.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

/cc @mauriciopoppe

[mauriciopoppe]

This should fix the issue in https://prow.k8s.io/view/gs/kubernetes-jenkins/logs/post-csi-proxy-push-images/1587109032290684928

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alexander-ding, mauriciopoppe

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