workflow-templates/knative-go-build.yaml does also testing

This workflow action actually does a `go test` which IMO has some overlap with `knative-go-test.yaml`.

I wonder whether this file is required at all and whether the testing in `knative-go-test.yaml` is not good enough ?

Compare workflow-templates/knative-go-build.yaml with workflow-templates/knative-go-test.yaml, starting with their Go testing steps and the purpose of each workflow. Determine whether the testing overlaps and whether both files are required; done means the workflows have one clear, agreed testing responsibility.

Written by the indexing model from the issue text.