Fixed docker registry naming issue

[rbinrais]

Dockerfile generated by CLI for input_reader and output_writer has a missing "/" when referring to docker registry name and the image name. This cause DevOps CI pipeline to fail. Fix is to add the "/" to separate registry name with the image name properly.

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[rbinrais]

Updated PR title to reflect it is to resolve a bug.

[sayar]

@margaretmeehan and @rbinrais this breaks the CLI as some of the config options in devops require a url ending without a slash while the docker files expect a slash. The CLI programmatically adds the slash where necessary. This is only an issue encountered if you don't use the CLI to generate the pipelines and go straight to the Git repo. I will submit a PR documenting this issue but closing this PR for now.