Validate released operator image by digest.

[Paamicky]

Description:

Adds the ability to run the operator integration test against a pre-built image (digest) so we validate the exact artifact being released.
Backlog issue: https://issues.amazon.com/issues/CWQS-2726

Changes

• Added optional workflow_dispatch/workflow_call inputs to operator-integration-test.yml: operator-image-uri, operator-image-digest, region.
• New composite action: builds from source when no digest is given (unchanged PR/push behavior), or pulls the released image by digest and loads it into minikube.
• All 5 jobs now use the composite action and deploy with the resolved image.

Testing

• workflow run with real operator digest: operator_test

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[AshuSrv]

I know this is not part of this PR but maybe something to consider is if we are triggering manual run and at the same time some one merges a PR it will cancel our manual run, do we want this behaviour?

[Paamicky]

yes because a merge to main takes top priority as we care about what was just merged, rather than the manual one. A manual run of your branch won't get cancelled.