🐛 fix path of uploaded artifacts

[sbueringer]

What this PR does / why we need it:

Nightly and postsubmit artifacts are currently uploaded to:

• https://storage.googleapis.com/artifacts.k8s-staging-capi-openstack.appspot.com/components/nightly_master_20210403

this should actually be, e.g.:

• https://storage.googleapis.com/artifacts.k8s-staging-capi-openstack.appspot.com/components/nightly_master_20210403/infrastructure-components.yaml

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• if necessary:
  • includes documentation
  • adds unit tests

/hold

[k8s-ci-robot]

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This pull-request has been approved by: sbueringer

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[jichenjc]

/lgtm
/hold cancel