Add sourceArn to sts through headers

[haoranleo]

What this PR does / why we need it:
Cherry-pick from #749

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 #

[k8s-ci-robot]

Hi @haoranleo. Thanks for your PR.

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[micahhausler]

/ok-to-test

[micahhausler]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: haoranleo, micahhausler

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