Speed up testing by priming Kind cluster's docker registry with all required images

**Is your feature request related to a problem? Please describe.**
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Slow tests since all images need to be pulled from the remote docker registries for the first test case.

**Describe the solution you'd like**
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Prime the Kind docker registry by prepopulating it with bookinfo, ambassador and workflow executor images.

**Describe alternatives you've considered**
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**Additional context**
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The issue concerns the Kind cluster's Docker registry used by tests; first locate the test-cluster setup and registry initialization entry point, then identify how the bookinfo, ambassador, and workflow executor images are obtained. Done means those images are available in the local registry before the first test case and test startup completes successfully.

Written by the indexing model from the issue text.