🐛 [RELEASE-2.3] Changes to release process

[richardcase]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Changes from the failed releases:

• Including the toolchain directive
• Bumping the GCB image so that it has a newer Go version (that understands the toolchain directive)
• Changing the clusterawsadm build to be inline with CAPI

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

Relates #4812

Special notes for your reviewer:

This re-adds some of the changes from #4803 (by @damdo ) with changes to GCB.

Checklist:

• squashed commits
• includes documentation
• includes emojis
• adds unit tests
• adds or updates e2e tests

Release note:

Various changes to the releases process.

[damdo]

/lgtm

[faiq]

/lgtm

same thing looks good, but the same question from #4813 -- why do we need that user argument to the docker command?

[richardcase]

After 2 lgtm:

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: richardcase

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