Update images to latest and fix boskos

[chizhg]

What this PR does, why we need it:

1. Make the same change as Add Boskos CRDs to prow/cluster, and bump Boskos back to latest kubernetes/test-infra#16267 to fix the boskos breaking change
2. Revert the revert for Update prow to v20200212-1f7b8ac1d #1716 to update the images
3. Boskos has another bug fix in boskos: disable controller-runtime manager metrics kubernetes/test-infra#16270, and the image updated by the prow-auto-bumper was before this fix, so bump boskos to v20200217-8ab6e0b2c to pick it up

I have tested on the staging-prow cluster and everything works.

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[chaodaiG]

/lgtm