We need to have an ability fix test workspace stack images addresses using dedicated variable CRW_STACK_IMAGE_REGISTRY on-fly before running the tests.
There is commit which partly implements this.
Update: it was decided to read map for replacement from pre-defined place test/codeready-test-e2e/src/test/resources/conf/stack-replacement.json for the sake of simplicity.
Also, there is ready-to-use map to quay.io latest tags https://github.com/redhat-developer/codeready-workspaces/blob/master/test/codeready-test-e2e/src/test/resources/conf/stack-replacement-quay-latest.json.